Leukopoiesis Powerpoint 2012

Powerpoint untuk blok Hematology semester III tahun 2012 dengan topik Leukopoiesis. Presentasi ini membahas tentang pembentukan leukosit yang dibagi menjadi : granulocytopoiesis yaitu pembentukan granulosit (neutrofil, basofil dan eosinofil), monocytopoiesis yaitu pembentukan monosit dan lymphopoiesis yaitu pembentukan limfosit.



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Posted in 2012 , hematology , hematopoiesis , power point

LEUKOPOIESIS

Granulopoiesis

The maturation process of granulocytes takes place with cytoplasmic changes characterized by the synthesis of a number of proteins that are packed in two organelles: the azurophilic and specific granules. These proteins are produced in the rough endoplasmic reticulum and the Golgi complex in two successive stages. The first stage results in the production of the azurophilic granules, which stain with basic dyes in the Wright or Giemsa methods and contain enzymes of the lysosomal system. In the second stage, a change in synthetic activity takes place with the production of several proteins that are packed in the specific granules. These granules contain different proteins in each of the three types of granulocytes and are utilized for the various activities of each type of granulocyte.

 

Maturation of Granulocytes

The myeloblast is the most immature recognizable cell in the myeloid series. It has a finely dispersed chromatin, and nucleoli can be seen. In the next stage, the promyelocyte is characterized by its basophilic cytoplasm and azurophilic granules. These granules contain lysosomal enzymes and myeloperoxidase. The promyelocyte gives rise to the three known types of granulocyte. The first sign of differentiation appears in the myelocytes, in which specific granules gradually increase in quantity and eventually occupy most of the cytoplasm. These neutrophilic, basophilic, and eosinophilic  myelocytes mature with further condensation of the nucleus and a considerable increase in their specific granule content. Before its complete maturation, the neutrophilic granulocyte passes through an intermediate stage in which its nucleus has the form of a curved rod (band cell).

 

Maturation of Lymphocytes & Monocytes

Study of the precursor cells of lymphocytes and monocytes is difficult, because these cells do not contain specific cytoplasmic granules or nuclear lobulation, both of which facilitate the distinction between young and mature forms of granulocytes. Lymphocytes and monocytes are distinguished mainly on the basis of size, chromatin structure, and the presence of nucleoli in smear preparations. As lymphocyte cells mature, their chromatin becomes more compact, nucleoli become less visible, and the cells decrease in size. In addition, subsets of the lymphocyte series acquire distinctive cell-surface receptors during differentiation that can be detected by immunocytochemical techniques.

Lymphocytes

Circulating lymphocytes originate mainly in the thymus and the peripheral lymphoid organs (eg, spleen, lymph nodes, tonsils). However, all lymphocyte progenitor cells originate in the bone marrow. Some of these lymphocytes migrate to the thymus, where they acquire the full attributes of T lymphocytes. Subsequently, T lymphocytes populate specific regions of peripheral lymphoid organs. Other bone marrow lymphocytes differentiate into B lymphocytes in the bone marrow and then migrate to peripheral lymphoid organs, where they inhabit and multiply in their own special compartments.

The first identifiable progenitor of lymphoid cells is the lymphoblast, a large cell and dividing two or three times to form prolymphocytes. Prolymphocytes are smaller and have relatively more condensed chromatin but none of the cell-surface antigens that mark prolymphocytes as T or B lymphocytes. In the bone marrow and in the thymus, these cells synthesize cell-surface receptors characteristic of their lineage, but they are not recognizable as distinct B or T lymphocytes in routine histological procedures. Using immunocytochemical techniques makes the distinction.

 

Monocytes

The monoblast is a committed progenitor cell that is almost identical to the myeloblast in its morphological characteristics. Further differentiation leads to the promonocyte, a large cell (up to 18 um in diameter) with a basophilic cytoplasm and a large, slightly indented nucleus. The chromatin is lacy, and nucleoli are evident. Promonocytes divide twice in the course of their development into monocytes. A large amount of rough endoplasmic reticulum is present, as is an extensive Golgi complex in which granule condensation can be seen to be taking place. These granules are primary lysosomes, which are observed as fine azurophilic granules in blood monocytes. Mature monocytes enter the bloodstream, circulate for about 8 h, and then enter the connective tissues, where they mature into macrophages and function for several months.

 

source : Basic Histology

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Posted in 2012 , hematology , materi kuliah

Cara Menulis Summary Jurnal (How to Write a Summary)

Saat ini saya sedang membimbing beberapa mahasiswa pada program Special Study di Fakultas kedokteran Universitas Udayana. Pada tahap pertama yaitu pada semester II tujuannya adalah mengajarkan kepada mahasiswa untuk bisa mencari bahan bacaan /refference yang sesuai dengan judul dan kemudian bisa membuat summary/rungkasan dari masing-masing jurnal.

Dari  pengalaman saya membimbing mahasiswa, ternyata masih banyak yang belum memahami bagaimana cara membuat summary jurnal yang baik. Berikut ini adalah cara membuat summary/ringkasan jurnal yang baik, yang dikutip dari http://www.enotes.com/topics/how-write-summary

How to Write a Summary in 8 Easy Steps

Writing a good summary demonstrates that you clearly understand a text...and that you can communicate that understanding to your readers. A summary can be tricky to write at first because it’s tempting to include too much or too little information. But by following our easy 8-step method, you will be able to summarize texts quickly and successfully for any class or subject.

1) Divide…and conquer. First off, skim the text you are going to summarize and divide it into sections. Focus on any headings and subheadings. Also look at any bold-faced terms and make sure you understand them before you read. 

2) Read. Now that you’ve prepared, go ahead and read the selection. Read straight through. At this point, you don’t need to stop to look up anything that gives you trouble—just get a feel for the author’s tone, style, and main idea.

3) Reread. Rereading should be active reading. Underline topic sentences and key facts. Label areas that you want to refer to as you write your summary. Also label areas that should be avoided because the details—though they may be interesting—are too specific. Identify areas that you do not understand and try to clarify those points. 

4) One sentence at a time. You should now have a firm grasp on the text you will be summarizing. In steps 1–3, you divided the piece into sections and located the author’s main ideas and points. Now write down the main idea of each section in one well-developed sentence. Make sure that what you include in your sentences are key points, not minor details. 

5) Write a thesis statement. This is the key to any well-written summary. Review the sentences you wrote in step 4. From them, you should be able to create a thesis statement that clearly communicates what the entire text was trying to achieve. If you find that you are not able to do this step, then you should go back and make sure your sentences actually addressed key points.

6) Ready to write. At this point, your first draft is virtually done. You can use the thesis statement as the introductory sentence of your summary, and your other sentences can make up the body. Make sure that they are in order. Add some transition words (then, however, also, moreover) that help with the overall structure and flow of the summary. And once you are actually putting pen to paper (or fingers to keys!), remember these tips:

• Write in the present tense.
• Make sure to include the author and title of the work.
• Be concise: a summary should not be equal in length to the original text.
• If you must use the words of the author, cite them.
• Don't put your own opinions, ideas, or interpretations into the summary. The purpose of writing a summary is to accurately represent what the author wanted to say, not to provide a critique.

7) Check for accuracy. Reread your summary and make certain that you have accurately represented the author’s ideas and key points. Make sure that you have correctly cited anything directly quoted from the text. Also check to make sure that your text does not contain your own commentary on the piece. 

8) Revise. Once you are certain that your summary is accurate, you should (as with any piece of writing) revise it for style, grammar, and punctuation. If you have time, give your summary to someone else to read. This person should be able to understand the main text based on your summary alone. If he or she does not, you may have focused too much on one area of the piece and not enough on the author’s main idea.

Demikianlah cara menulis summary jurnal yang baik, semoga bermanfaat 

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Posted in 2012 , artikel

Pengantar Praktikum Female Genital Histology

Berikut ini adalah panduan praktikum Female Genital Histology pada blok The Reproductive System and Disorders yang dilaksanakan pada hari Jumat tanggal 13 Juli 2012. Pada Praktikum ini ada 7 Slide dengan kode F1 sampai F7. Isi masing-masing slide bisa dibaca pada penjelasan dibawah ini. 

OBJECTIVES:

1. Understand and identify the stages of follicular growth (primordial, primary, secondary, tertiary), as well as the changes that occur in the follicular wall during pregnancy.
2. Identify the structure of the oviduct.
3. Describe the changes that occur in endometrium during the menstrual cycle as well as the changes that occur during pregnancy.
4. Identify the structure of the vagina

SLIDE F7 (Ovarium)

Pada Slide ini Anda bisa mengamati struktur mikroskopik ovarium dan juga oviducts. Sebelum Anda mulai melihat slide coba ingat kembali struktur mikroskopis ovarium, dan ingat apa yang terjadi pada ovarium pada setiap siklusnya (fase proliferasi, ovulasi dan luteal)

Mulailah mengamati dengan pembesaran kecil, amati keseluruhan ovarium. Identifikasi jaringan ikat yang membungkus keseluruhan ovarium yaitu tunika albugenia. Coba identifikasi epitel yang melapisi bagian luar tunika albugenia yang disebut germinal epithelium. (contoh)

Kemudian geser pengamatan kearah lebih dalam dari tunika albugenia, coba identifikasi folikel primordial yang terbenam diantara stroma jaringan ikat. (berapakah jumlah spermatogonia saat lahir dan berapa jumlahnya saat pubertas???).

Folikel primordial terdiri dari satu oosit primer dikelilingi oleh lapisan sel folikel pipih. Kemudian coba identifikasi folikel yang mempunyai ukuran lebih besar dari folikel primordial dan terletak lebih dalam (ke arah medulla), yaitu folikel primer [contoh] di mana oosit besar dikelilingi oleh lapisan sel folikuler kuboid. (sebutkan dua jenis foliker primer !!!) . Diantara oosit dan sel granulosa coba identifikasi sebuah lapisan bening yang disebut zona pelusida.

Kemudian identifikasi folikel dengan ukuran lebih besar dengan ruangan didalamnya, yang disebut folikel sekunder. [contoh]. Folikel sekunder memiliki ruangan diantara sel granulosa yang disebut antrum.  Coba identifikasi oosit, cumulus oophorus, corona radiata, zona dan zona pellucida. Amati juga jaringan ikat disekitar folikel !!!. (Coba ingat kembali tentang teka interna dan teka eksterna beserta fungsinya !!!). 

Dengan perkembangan lebih lanjut, folikel sekunder menjadi folikel de Graafian [contoh]. Folikel ini memiliki ukuran paling besar.  Oosit telah mencapai ukuran penuh, terletak eksentrik dalam folikel dibungkus oleh  cumulus oophorus. Antrum semakin besar dan dinding folikel semakin tipis. Pada pertengahan siklus, satu folikel akan mengalami ovulasi. Coba jelaskan proses ovulasi !!!!

SLIDE F1 (Corpus Luteum)

Pada slide ini coba amati struktur berlipat-lipat dengan ukuran cukup besar di dalam ovarium. Ini adalah corpus luteum (contoh) . Coba jelaskan proses pembetunkan corpus luteum setelah proses ovulasi !!! , kemudian jelaskan  nasib korpus luteum !!!!

SLIDE F2, F3, DAN F4 (Endometrium)

Slide F2 sampai F4 adalah endometrium pada berbagai tahap siklus menstruasi. Sebelum mulai mengamati slide coba ingat struktur mikroskopis uterus yang terdiri dari endometrium, myometrium dan adventisia. Pelajari lagi perubhan yang terjadi pada endometrium pada tahap proliferasi, sekresi dan menstrusi. Ingat kembali pengertian stratum basalis dan fungsional dari endometrium. Pelajari pengaturan hormon pada siklus menstruasi!!!

SLIDE F2

Fase menstruasi terjadi pada hari 1-4 dari siklus menstruasi. Pada fase ini telah terjadi pelepasan stratum functionalis dan yang tersisa hanyalah stratum basalis.  Coba identifikasi myometrium yang tebal kemudian identifikasi lapisan endometrium yang relatif tipis dengan sisa-sisa kelenjar.(coba ceritakan proses menstruasi !!!!)

SLIDE F3

Fase proliferatif (hari 5-14 siklus menstruasi). Pada fase ini lapisan fungsional endometrium kempali dibentuk. Endometrium menjadi lebih tebal, dan kelenjar mempunyai bentuk lurus. Coba identifikasi myometrium dan kemudian identifikasi endometrium dengan kelenjarnya yang berbentuk lurus. (Coba ceritakan struktur ovarium pada saat endometrium berada pada fase ini !!!! dan ceritakan hormon yang dominan pada fase ini !!!!)

 SLIDE F4

Fase Sekresi (hari 15-28 siklus menstruasi) Pada fase ini kelenjar endometrium mulai menghasilkan sekresi dan mempunyai struktur yang berkelok-kelok (coiled). Endometrium mencapai ketebalan maksimal selama periode ini, dan arteri spiral terus tumbuh dan meluas ke daerah dangkal dari lapisan fungsional. Ada juga infiltrasi leukosit yang cukup besar dalam stroma.

Coba identifikasi myometrium,kemudian identifikasi myometrium yang tebal dengan kelenjar yang berkelok-kelok.

(coba jelaskan apa yang terjadi pada ovarium pada saat endometrium berada pada fase ini, dan ceritakan hormon yang dominan pada fase ini !!!, Jelaskan juga apa yang terjadi pada endometrium jika oosit dibuahi (fertilisasi) dan jika oosit tidak dibuahi!!!!)

SLIDE F6 (Oviduct)

Sebelum mempelajari slide ini coba ingat lagi tentang pembagian anatomis dari oviduct, pelajari juga tentang fungsi dari oviduct !!!!

Dengan perbesaran kecil amati lipatan-lipatan mukosa yang dilapisi oleh epitel, amati juga lapisan-lapisan pada dinding oviduct. (coba sebutkan lapisan pada dinding odviduct!!!!) (contoh)

Kemudian dengan perbesaran lebih kuat coba identifikasi epitel yang melapisi lumen oviduct. Kemudian amati otot polos yang melapisi dinding oviduct !!!.

(Coba jelaskan struktur pada oviduct yang berperan dalam transport oosit !!! dan jelaskan fungsi sekresi yang dihasilkan oleh sel-sel epitel !!!!)

SLIDE F5 (vagina)

Pada perbesaran rendah, perhatikan tiga lapis dinding vagina: lapisan mukosa, lapisan otot polos, dan lapisan adventitia. Perhatikan epitel yang melapisi vagina berupa stratified squamous epithelium yang sangat tebal !!!!! (contoh) (Jelaskan komponen yang terdapat pada sel epitel yang menyebabkan vagina memiliki suasana agak asam !!!!)

Jaringan lamina propria berisi banyak sabut elastis dan serat kolagen. Lapisan otot polos terdiri dari lapisan sirkular didalam dan lapisan longitudinal di luar.

disusun oleh : dr. I Wayan Sugiritama, M.Kes


Anda Bisa Download Versi PDF di alamat ini : PENGANTAR PRAKTIKUM FEMALE GENITAL HISTOLOGY

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Posted in 2012 , female reproductive system , praktikum

Pengantar Praktikum Male Genital Histology

Berikut ini adalah pengantar praktikum histologi Blok Genital System and Disorders yang dilaksanakan pada hari Jumat tanggal 13 Juli 2012. Pada praktikum ini disediakan 7 slide histologi dengan kode M1 sampai M7. Untuk penjelasan masing-masing slide bisa dibaca pada keterangan dibawah ini :

OBJECTIVES :

1. Recognize germ cells at different steps of spermatogenesis in the seminiferous tubule.
2. Recognize Sertoli cells and Leydig cells, and explain their roles in the production of sperm and regulation of the male reproductive system.
3. Recognize the various parts of the male reproductive tract in histological section, and explain the contribution of each part to the production of semen for the final ejaculate.
4. Recognize and understand the histological organization of the prostate gland, Seminal vesicle gland dan Bulbourethral Glands 

TESTIS

Slide (M1) :

Pada slide ini Anda bisa mengamati parenkim testis yang dibungkus oleh kapsul tunika albugenia yang terdiri dari jaringan ikat padat. Dalam testis Anda akan melihat  berbagai bentuk tubulus seminiferus , dengan jaringan interstitial diantaranya. Dalam jaringan interstitial diantara tubulus seminiferus cobalah identifikasi kelompok sel Leydig (bisa dengan pembesaran yang lebih besar), yang mensekresikan hormon testosteron. Pada jaringan interstitial juga bisa dilihat pembuluh darah dan sel-sel yang lebih kecil yang merupakan sel dari jaringan ikat longgar.

Sekarang fokuskan pengamatan pada tubulus seminiferus dan gunakan lensa obyektif yang lebih kuat. Setiap tubulus seminiferus dikelilingi oleh lapisan pembatas yaitu tunika propria, terdiri dari sel pipih. Sel-sel besar yang terletak dekat dengan membran basal dan memiliki inti bulat adalah spermatogonium . Sekarang geser pengamatan kearah lebih dalam dari tubulus seminiferus dan coba identifikasi spermatosit primer yang mempunyai ciri : sel berukuran besar,dengan inti besar ditengahnya. Spermatosit sekunder tidak mudah ditemukan karena setelah terbentuk dalam waktu singkat langsung mengalami mitosis menjadi spermatid

Semua sel-sel yang lebih kecil di bagian atas epitel (dekat delan lumen tubulus) adalah spermatid dalam berbagai tahap diferensiasi untuk menjadi spermatozoa. Para spermatid awalnya memiliki inti bulat, tetapi secara bertahap menjadi lebih kecil, lebih padat dan menyerupai bentuk kepala sperma.

Sekarang coba identifikasi  sel Sertoli dengan ciri-ciri : nukleus yang besar, relatif pucat dan tidak teratur bentuknya. Diantara sel sertoli bisa diidentifikasi spermatogenic epitelium dalam berbagai derajat maturasi.

TIPS MEMBEDAKAN SEL SERTOLI, SPERMATOGONIUM DAN SPERMATOSIT PRIMER

Sel Sertoli menyelimuti sel-sel gamet selama proses maturasinya. Sel Sertoli dapat dibedakan karena mereka memiliki warna pucat dengan nukleus berbentuk oval inti dan bentuk sel yang tidak beraturan, batas antar sel tidak jelas Inti

Spermatogonia adalah sel-sel prekursor yang besar dan selalu terletak di sepanjang membran basal tubulus.

Spermatosit primer memiliki ukuran paling besar (diantara sel-sel gamet), inti heterochromatic, dan mereka terletak di antara membran basal dan lumen tubulus.

 SLIDE M3
Pada slide ini selain bisa mengamati parenkim testis yang dibungkus tunika albugenia, Anda juga bisa mengamati mediastinum testis dengan rete testis didalamnya, ductus epididymis dan awal dari ductus deferents.
Dengan pembesaran kecil coba identifikasi testis yang dibungkus tunika albugenia dengan tubulus seminiferus didalamnya. Coba ingat kembali perjalanan spermatozoa setelah dilepas dari tubulus seminiferus, ductus apakah yang dilewati hingga spermatozoa mencapai epididymis dimana spermatozoa akan disimpan sampai saatnya ejakulasi?
Coba geser pengamatan Anda sepanjang tunika albugenia dan temukan bagian tunika albugenia yang paling tebal, bagian ini disebut mediastinum. Didalam mediastinum coba identifikasi saluran-saluran dengan bentuk tidak teratur yang disebut sebagai rete testis. Ductus apakah yang dilewati spermatozoa sebelum mencapai rete testis ??? dan bagaimanakan strukturnya ???
Amati bahwa rete testis dilapisi oleh sel epitel kuboid dan Anda mungkin melihat mikrovili dibagian atas epitel. 

Sekarang kembali dengan pembesaran kecil dan pindahkan pengamatan kebagian slide yang berada diluar tunika albugenia. Coba amati adanya epididymis !!!!. Sekarang dengan pembesaran lebih kuar amati struktur mikroskopik epididymis !!! Epididymis dilapisi oleh pseudostratified columnar epithelium dengan stereocilli dipermukaannya.  Anda mungkin dapat melihat lapisan tipis otot polos di sekitar tubulus, yang mungkin bertindak dengan gerakan peristaltik untuk memindahkan sperma bersama. (Apa yang dimaksud dengan steterocillia ???? Coba ingat proses pematangan spermatozoa yang terjadi di epididymis!!!!)

Pada slide ini Anda juga bisa mengamati bagian awal dari vas deferens!!! Coba amati strukturnya dan bandingkan dengan struktur pada slide M5 !!!!

SLIDE M2
Pada slide ini bisa diamati epididymis, Anda bisa mengamati epididymis yang berupa tabung dengan spermatozoa dilumennya. Coba identifikasi epitel yang melapisi dinding epididymis dan identifikasi otot polos pada dindingnya !!!

SLIDE M5

Pada slide ini Anda bisa mengamati struktus mikroskopis vas/ductus deferens. Dengan pembesaran kecil coba amati struktur spernti tabung yang berada ditengah-tengah slide, sekarang coba dengan pembesaran yang lebih kuat. Coba identifikasi lapisan-lapisan pada dinding vas deferens !!!

Identifikasi epitel yang melapisi vas deferens yang dilapisi oleh pseudostratified epithelum, kemudian amati lapisan otot polos yang sangat tebal dan lapisan jaringan ikat dibagian paling luar.

Coba ingat fungsi dari vas deferens yang mempunyai lapisan otot polos yang tebal !!!! kemudian pelajari perubahan struktur vas deferens ketika mendekati prostat !!!!

SLIDE M4

Pada slide ini Anda bisa mengamati struktur mikroskopis asesori glands yaitu vesikula seminalis. Identifikasi lipatan-lipatan mukosa yang dilapisi oleh epitel simple columnar sampai pseudostratifed columnar epithelium. Pada dindingnya coba identifikasi lapisan otot polos yang cukup banyak.

Ingat kembali tentang fungsi kelenjar vesikula seminalis !!! Bagamana karakteristik sekresinya ??? Berapa persen kontribusinya pada total volume semen ?? dan apa fungsi sekret dari vesikula seminalis ???

SLIDE M6

Pada slide ini Anda bisa mengamati struktur mikroskopik kelenjar prostat. Kelenjar terdiri dari 15-30 kelenjar tubuloalveolar yang mengeluarkan sekresinya secara terpisah ke dalam uretra. Coba identifikasi unit sekresi kelenjar prostat yang dilapisi simple columnar epithelium. Unit sekresi kelenjar prostat dilapisi oleh otot polos yang cukup tebal. Pada slide ini Anda juga bisa mengidentifikasi ductus-ductus kelenjar prostat.

Coba ingat tentang karakteristik sekresi kelenjar prostat dan fungsinya !!!!! Dan pelajari tentang pembagian zona pada kelenjar prostat dan peran pentingnya diklinik !!!!

SLIDE M7

Pada Slide ini Anda bisa mengamati struktur mikroskopis kelenjar Bulbourethral. Coba identifikasi unit sekresinya yang dilapisi oleh simple cuboidal epithelium, pada stroma Anda juga bisa mengamati adanya otot polos. Coba ingat kembali tentang karakteristik sekresi kelenjar Bulbourethral dan fungsinya !!!!

disusun oleh dr. I Wayan Sugiritama, M.Kes

Anda Bisa Download Versi PDF di alamat ini : PENGANTAR PRAKTIKUM MALE GENITAL HISTOLOGY

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Posted in 2012 , male genital system , praktikum

Sperm transport in the female reproductive tract

Spermatozoa are actively transported from the vagina via the cervical canal and the uterine cavity to the ampulla of the oviducts, where fertilization occurs. In the human vagina, the ejaculated semen is deposited near the external cervical opening where the environment is very acidic due to lactic acid and thus hostile to spermatozoa (Harper 1988). The alkaline pH of the ejaculate protects spermatozoa in this acidic environment (Speroff et al. 1994). This protection is, however, temporal, and most spermatozoa only remain motile in the vagina for a few hours (Fordney-Settlage 1981, Speroff et al. 1994). The spermatozoa are transported into the cervical canal by the pressure alterations in the vagina due to the female orgasm assisted by the normal motility of sperm (Fox et al. 1970, Speroff et al. 1994). During their transit in the female reproductive tract, the spermatozoa are stored in cervical crypts (Harper 1988). The passage of spermatozoa through the cervix is thought to maintain the muscle contractions of the reproductive tract wall and some properties of the spermatozoa. The interactions between sperm and mucus and the motility of spermatozoa during the transport are important, and one cause of infertility is presumably the impaired sperm movement through cervical mucus (Speroff et al. 1994). The change in the composition of cervival mucus at mid-cycle also affects the passage (Fordney-Settlage 1981, Harper 1988, Barratt & Cooke 1991). 

The release of spermatozoa from human cervical crypts may continue for several days (Yanagimachi 1994). Motile sperm has been recovered in the uterine cavity up to 24 h after intercourse (Rubinstein et al. 1951, Moyer et al. 1970), occasionally even at 85 h (Harper 1988). The transport of spermatozoa from the cervix to the uterotubal junction is mainly attributable to uterine wall contractions (Yanagimachi 1994). The human endometrium prepares for ovulation by secreting a unique kind of fluid to the uterine lumen. The fluid has a different protein pattern, ionic composition, and volume than at the other stages of the cycle (Casslén & Nilsson 1984, Casslén 1986, Harper 1988). This fluid serves to suspend spermatozoa and to keep them viable during the transport process, and it also contains macrophages that remove dead and nonviable spermatozoa. 

The uterotubal junction and the lower isthmus in some animals act as a site of storage for spermatozoa before the arrival of the ovum to the site of fertilization (Suarez 1998). During their storage, spermatozoa remain weakly motile and attached to the mucosal surface of luminal epithelial cells, especially in specific epithelial crypts (Cooper et al. 1979, Yanagimachi 1994, Suarez 1998). Whether the human oviduct has this function is, however, not fully determined (Harper 1988, Williams et al. 1993, Baillie et al. 1997). 

The ampulla of the oviduct is the site of fertilization, and motile spermatozoa can be found there up to 85 h after intercourse. The transport of spermatozoa through the oviducts is a combination of sperm motility, fluid flow, and contractive movements of the oviduct walls (Harper 1988). 

During its transport in the female reproductive tract, spermatozoa first undergo a maturational change called capacitation. Capacitation includes a variety of changes in the sperm plasma membrane, intracellular ions, metabolism, adenylate cyclase-cAMP system, nucleus, and acrosome (Yanagimachi 1994, Fraser 1995). Human spermatozoa do not need to experience the uterus or the isthmic region of the oviduct to became capacitated, and it has been proposed that capacitation is initiated and possibly already completed in the cervix (Speroff et al. 1994, Yanagimachi 1994). 

 Capacitation is followed by an acrosome reaction, which occurs when spermatozoa come into close contact with the ovum in the ampulla of the oviduct. The acrosome reaction enables spermatozoa to penetrate through the zona pellucida and fuse with the egg plasma membrane. In this reaction, the plasma membrane and the outer acrosomal membrane fuse, enabling release of the acrosomal content. Acrosome contains certain enzymes, e.g. hyaluronidase and acrosin, important for the events preceding fertilization (Yanagimachi 1994).  

Sperm hyperactivation occurs before the acrosome reaction (Yanagimachi 1994). Hyperactivation takes place in the oviduct and helps the spermatozoa to swim in the viscous oviduct fluid and to penetrate the zona pellucida (Stauss et al. 1995, Suarez 1996).

If fertilization occurs, the fertilized ovum enters the uterine lumen at the morula stage 4 days after ovulation. Approximately one day later, the morula develops into a blastocyst. Implantation begins about 7 days after ovulation. The implantation process involves apposition and adhesion of the blastocyst to the uterine surface, followed by invasion of the trophoblast. During apposition, uterine fluid is pinocytosed by microprotrusions of the apical surface of the luminal endometrial epithelium, resulting in a close association of the blastocyst with the uterine epithelium. Apposition is followed by adhesion of the outer layer of the trophoblast cells to the uterine epithelium, which initiates the invasion of trophoblasts. In humans, the invasion process is called interstitial invasion, since the syncytiotrophoblasts invade first between uterine epithelial cells and thereafter through the basal lamina (Klentzeris 1997).


source : http://herkules.oulu.fi/isbn9514266641/html/x480.html

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Sperm maturation and transport in the male reproductive tract

The spermatozoa are formed within the seminiferous tubules of the testes in a complex process called spermatogenesis. The continuous maintenance of this process is enabled by androgens secreted mainly by testicular Leydig cells located in the interstitial tissue outside the seminiferous tubules. In addition, the epididymal maturation of spermatozoa is also an androgen-dependent process (Robaire & Hermo 1988). 

Once formed within the seminiferous tubules, the immotile spermatozoa are released into luminal fluid and transported to the epididymis, where they gain the ability to move and fertilize the ovum (Yanagimachi 1994). 

The testicular spermatozoa are transported passively to the rete testis, which is a branched reservoir of the openings of the seminiferous tubules. From the rete testis, the transport of spermatozoa to the epididymis takes place via the efferent ducts, whose number varies between studies and individuals (Stieve 1930, Holstein 1969, Jonté & Holstein 1987, Saitoh et al. 1990). The epithelium lining these ducts is columnar and consists of two cell types called ciliated and nonciliated cells (Robaire & Hermo 1988). Both cell types are capable of performing endocytosis, and ciliated cells also maintain the movement of luminal fluid and sperms. Nonciliated cells are mainly responsible for the absorption of water and ions. 

The efferent ducts absorb most of the fluid discharged from the testis with spermatozoa, thus increasing the epididymal sperm concentration (Clulow et al. 1994).

The epididymis can be divided into three parts, called caput, corpus, and cauda. In the human epididymis, the caput is mainly filled by efferent ducts, which open to the epididymal duct near the border between the caput and corpus (Saitoh et al. 1990, Yeung et al. 1991). The human ductus epididymis contains four types of epithelial cells called principal cells, basal cells, apical mitochondria-rich cells (AMRC), and halo cells (Reid & Cleland 1957, Martan et al. 1964, Robaire & Hermo 1988, Palacios et al. 1991). Principal and basal cells are the main cell types, the former being involved in secretion and absorption, while the latter probably participate in detoxification processes or act as scavenger cells (Robaire & Hermo 1988, Veri et al. 1993, Yeung et al. 1994). 

In mammals, the transit of spermatozoa through the epididymis usually takes 10-13 days, whereas in humans the estimated transit time is 2-6 days (Amann & Howards 1980, Johnson & Varner 1988, Robaire & Hermo 1988). The epididymal segment where most spermatozoa attain their full fertilizing capacity appears to be the proximal cauda. The spermatozoa from that region are capable of moving progressively, which is characteristic of spermatozoa preceding fertilization, and bind to zona-free hamster ova in vitro at a higher percentage than spermatozoa obtained from more proximal locations (Yanagimachi 1994, Turner 1995). To attain the capacity to fertilize, sperm undergoes many maturational changes during its transit in the epididymal duct (Yanagimachi 1994). These include, for instance, changes in plasma membrane lipids, proteins and glycosylation, alterations in the outer acrosomal membrane, gross morphological changes in acrosome in some species, and cross-linking of nuclear protamines and proteins of the outer dense fiber and fibrous sheath. Numerous studies have questioned whether the human epididymal and efferent ducts are necessary for sperm maturation. In these studies, sperms that have bypassed the epididymis partly or completely or have also passed the efferent ducts and rete testis have still been able to fertilize eggs (Schyosman & Bedford 1986, Silber et al. 1988, Silber 1988, 1989, Schyosman 1993). However, these studies have been conducted on subjects with an abnormal reproductive tract, and spermatozoa aspirated from these subjects are not comparable to sperm aspirated from the corresponding segment in normal subjects. In addition, after surgical bypassing of the proximal excurrent ducts, vas deferens may become able to substitute the bypassed segments. Thus, these studies may, misleadingly, underevaluate the importance of the human epididymis and efferent ducts in sperm maturation (Cooper 1993, Bedford 1994, Turner 1995, Jones 1999). Alternatively, the requirement for post-testicular sperm maturation is not so essential in men as in other mammals (Yanagimachi 1994, Jones 1999), or this maturation may be faster and require only a brief exposure to some part of the post-testicular tract (Bedford 1994, Turner 1995). The cauda epididymidis (and proximal ductus deferens) are the regions where spermatozoa are stored before ejaculation (Turner 1995, Jones 1999). When ejaculation occurs, the stored spermatozoa with the surrounding fluid are mixed with the alkaline secretions of the male accessory sex glands and deposited to the vagina.

source : http://herkules.oulu.fi/isbn9514266641/html/x460.html

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The Histology of Female Genital System Semester VI (2012)

Contents :
Female Reproductive System
Ovaries
Ovarian Follicles
Uterus
Menstrual Cycle
Mammary Gland


Female Reproductive System

The female reproductive system consists of the internal reproductive organs (the paired ovaries and oviducts, the uterus, and the vagina) and the external genitalia.

Although the mammary glands are not considered part of the female reproductive system, their physiology and function are so closely associated with the reproductive system.

Ovaries

The paired ovaries, located within the pelvis, are almond-shaped bodies 3 cm long, 1.5 to 2 cm wide, and 1 cm thick.

The surface epithelium covering the ovaries, called the germinal epithelium, is a modified peritoneum. Directly beneath this epithelium is the tunica albuginea, the connective tissue capsule whose collagen fibers are oriented parallel to the ovary surface.

Each ovary is subdivided into the highly cellular cortex and a medulla.

The ovarian cortex is composed of a connective tissue framework, the stroma, housing fibroblast-like stromal cells as well as ovarian follicles in various stages of development. The medulla contains large blood vessels, lymph vessels, and nerve fibers embedded in a connective tissue stroma.

Before the onset of puberty, all of the follicles of the ovarian cortex are in the primordial follicle stage. The pulsatile release of GnRH from the hypothalamus results in a similar, pulsatile, release of gonadotropins (follicle-stimulating hormone [FSH], and leutinizing hormone [LH]) from the basophils of the anterior pituitary that culminates in the commencement of follicular development and the onset of the ovulatory cycle.

The development of the primary follicles is independent of FSH; differentiation and proliferation of the follicular cells are triggered by local factors secreted by cells of the ovary. Secondary and later follicles, however, are under the influence of FSH. Follicular development usually culminates in the release of a single oocyte (ovulation).

Ovarian Follicles

Ovarian follicles are surrounded by stromal tissue and consist of a primary oocyte and its associated follicular cells arranged in a single spherical layer or several concentric layers around the primary oocyte.

There are four identifiable stages of follicular development based on the growth of the follicle and the development of the oocyte: Primordial follicles, unilaminar and multilaminar primary follicles, secondary (antral) follicles, and Graafian (mature) follicles.

The development of the primordial and primary follicles is independent of FSH; instead, the differentiation and proliferation of the follicular cells are triggered by as yet uncharacterized local factors secreted by cells of the ovary. Secondary and later follicles, however, are under the influence of FSH. Follicular development usually culminates in the release of a single oocyte (ovulation).

Primordial follicles, the most primitive follicles, are abundant before birth, after which they become fewer in number. The primordial follicle is composed of a primary oocyte, arrested in the prophase stage of meiosis I, is surrounded by a single layer of flattened follicular cells.

Primary Follicle

Primordial follicles develop into primary follicles distinguished as a result of changes in the primary oocyte, the follicular cells, and the surrounding stromal tissue.

The primary oocyte grows to about 100 to 150 μm in diameter with an enlarged nucleus (sometimes called the germinal vesicle).

Follicular cells become cuboidal in shape. As long as only a single layer of follicular cells encircles the oocyte, the follicle is called a unilaminar primary follicle. When the follicular cells proliferate and stratify, forming several layers of cells around the primary oocyte, the follicle is called a multilaminar primary follicle, and the follicular cells are more commonly referred to as granulosa cells.

During this stage, an amorphous substance (the zona pellucida) appears, separating the oocyte from the surrounding follicular cells. Microvilli of the oocyte and filopodia of the follicular cells invade the zonula pellucida and form gap junctions through which they communicate throughout follicular development.

Stromal cells form an inner theca interna, composed mostly of a richly vascularized cellular layer, and an outer theca externa, composed mostly of fibrous connective tissue. The theca interna cells produce the male sex hormone androstenedione, which enters the granulosa cells, where it is converted by the enzyme aromatase into the estrogen estradiol. The granulosa cells are separated from the theca interna by a thickened basal lamina.

Secondary Follicle

Secondary follicles are similar to primary follicles except for the presence of accumulations of liquor folliculi among the granulosa cells.

Continued proliferation of the granulosa cells of the secondary follicle depends on FSH released by basophil cells of the anterior pituitary.

As more fluid is produced, individual droplets of liquor folliculi coalesce to form a single, fluid-filled chamber, the antrum. The granulosa cells become rearranged so that the primary oocyte is now surrounded by a small group of granulosa cells that project out from the wall into the fluid-filled antrum. This structure is called the cumulus oophorus. The loosely arranged low cuboidal granulosa cells immediately adjacent to the zona pellucida move slightly away from the oocyte, but their filopodia remain within the zona pellucida, maintaining contact with the primary oocyte. This single layer of granulosa cells that immediately surrounds the primary oocyte is called the corona radiata.

Most of the follicles that reach this stage of development undergo atresia. A few secondary follicles continue to develop into mature follicles.

Graafian Follicles

Continued proliferation of the granulosa cells and continued formation of liquor folliculi result in the formation of a graafian (mature) follicle whose diameter reaches 2.5 cm by the time of ovulation. The graafian follicle may be observed as a transparent bulge on the surface of the ovary, nearly as large as the ovary itself.

The follicular cells of the wall of the follicle compose the membrana granulosa. Continued formation of liquor folliculi causes the cumulus oophorus composed of the primary oocyte, the corona radiata, and associated follicular cells to become detached from its base to float freely within the liquor folliculi.

By the 14th day of the menstrual cycle, estrogen produced mostly by the developing graafian follicle, but also by secondary follicles, causes elevation of blood estrogen to levels high enough to have the numerous effects, including the shutting off of FSH release and a surge in LH release.

The high blood levels of LH causes the completion of the first phase of meiosis I, resulting in the formation of the secondary oocyte. The secondary oocyte begins, and is arrested in, the metaphase stage of meiosis II. and is released from the graafian follice, a process known as ovulation.

The remnants of the graafian follicle are converted into the corpus hemorrhagicum and then the corpus luteum.

Uterus

The uterus, a single, thick, pear-shaped structure located in the midline of the pelvis, receives at its broad, closed end the terminals of the paired oviducts. It is divided into three regions, the body, fundus, and the cervix.

The uterine wall of the body and the fundus is composed of an endometrium, myometrium, and either an adventitia or a serosa.

The endometrium, or mucosal lining of the uterus, is composed of a simple columnar epithelium and a lamina propria. The epithelium is composed of nonciliated secretory columnar cells and ciliated cells, whereas the lamina propria houses simple branched tubular glands that extend as far as the myometrium The morphological and physiological alterations that occur in the endometrium during the phases of the menstrual cycle are controlled by various hormones.

The endometrium consists of two layers, the functionalis, a thick, superficial layer that is sloughed at menstruation and the basalis, a deep, narrow layer whose glands and connective tissue elements proliferate and thereby regenerate the functionalis during each menstrual cycle.

The functionalis is vascularized by numerous coiled helical arteries that supply the glands and connective tissue. The straight arteries are much shorter and supply only the basalis.

The myometrium is composed of inner longitudinal, middle circular, and outer longitudinal layers of smooth muscle.

Much of the anterior portion of the uterus is covered by adventitia , whereas the fundus and posterior portion of the body are covered by a serosa.

Menstrual Cycle

Menstruation, which begins on the day bleeding from the uterus starts, occurs when fertilization does not take place. The corpus luteum becomes nonfunctional about 14 days after ovulation, thus reducing the levels of progesterone and estrogen. Although the entire functionalis layer of the endometrium is sloughed, it is not completely released from the wall immediately; rather, this process continues for 3 to 4 days.

The proliferative phase (or follicular phase) occurs at the same time as the development of the ovarian follicles. It begins when the menstrual flow ceases, on about day 4, and continues through day 14 by which time the functionalis layer of the endometrium has been fully restored to its previous status with a full complement of epithelium, glands, stroma, and coiled arteries.

The secretory phase (or luteal phase) commences after ovulation. During this phase, the endometrium continues to thicken. The secretory products first accumulate in the basal region of the cytoplasm of the cells constituting the endometrial glands, the granules move apically, and are released into the lumen of the gland. This glycogen-rich material will nourish the conceptus before the formation of the placenta. The secretory phase completes the menstrual cycle as the 28th day approaches, presaging the menstrual phase of a new menstrual cycle.

Observe the correlation with the events occurring in the ovary as well as with the blood hormonal levels.

Mammary Gland

Mammary glands secrete milk, a fluid containing proteins, lipids, and lactose as well as lymphocytes and monocytes, antibodies, minerals, and fat-soluble vitamins.

The glands within the breasts are compound tubuloalveolar glands, consisting of 15 to 20 lobes radiating out from the nipple. Each lobe is drained by its own lactiferous duct where each duct is dilated to form a lactiferous sinus for milk storage and then narrows before reaching the nipple.

Resting or nonsecreting mammary glands of nonpregnant women have the same basic architecture as the lactating (active) mammary gland, except that they are smaller and without developed alveoli, which occur only during pregnancy.

Mammary glands are activated by elevated surges of estrogen and progesterone during pregnancy to become lactating glands to provide milk for the newborn. At this time, the terminal portions of the ducts branch and grow and the alveoli develop and mature

As pregnancy progresses, the breasts enlarge as a result of hypertrophy of the glandular parenchyma and engorgement with colostrum, a protein-rich fluid, in preparation for the newborn. Within a few days after birth, when estrogen and progesterone secretions have subsided, prolactin, secreted by acidophils of the anterior pituitary gland, activates the secretion of milk, which replaces the colostrum.

The secretions of the alveolar cells are of two kinds: lipids and proteins. Lipids are stored as droplets within the cytoplasm. They are released from the secretory cells, possibly by the apocrine mode of exocytosis. Proteins synthesized within these secretory cells are liberated from the cells by the merocrine mode of exocytosis.

Refferences :

• Color Textbook Histology, third edition, leslie P. Gartner
• Basic Histology, tenth edition, L. Carlos Junqueira,2003
• Histology and Cell Biology, second edition,2007
• Elsevier’s Integrated Histology,2007

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Posted in 2012 , genital system , lecture , materi kuliah , reproductive system

Histology of Male Genital System Semester VI (2012)

Contents :

The Male Genital System

The Testis

Spermatogenesis

Genital Ducts

Genital Accessory Glands

The Penis

The Male Genital System

The male reproductive (genital) system consists of the two testes suspended in the scrotum, a system of intratesticular and extratesticular genital ducts, associated glands, and the male copulatory organ, the penis. The testes are responsible for the formation of the male gametes, known as spermatozoa, as well as for the synthesis, storage, and release of the male sex hormone, testosterone.

The glands associated with the male reproductive tract are the paired seminal vesicles, the single prostate gland, and the two bulbourethral glands (of Cowper). These glands form the non-cellular portion of semen (spermatozoa suspended in the secretions of the accessory glands), which not only nourishes the spermatozoa but also provides a fluid vehicle for their delivery into the female reproductive tract.

The penis has a dual function: It delivers semen to the female reproductive tract during copulation and serves as the conduit of urine from the urinary bladder to outside the body.

TESTIS

Each testis is surrounded by a capsule known as the tunica albuginea. Immediately deep to this layer is a highly vascularized loose connective tissue, the tunica vasculosa. The posterior aspect of the tunica albuginea is somewhat thickened, forming the mediastinum testis, from which connective tissue septa radiate to subdivide each testis into approximately 250 compartments known as the lobuli testis

Each lobule has one to four blindly ending seminiferous tubules and small conglomerations of endocrine cells, the interstitial cells (of Leydig) which synthesize testosterone.

Spermatozoa, produced by the seminiferous epithelium of the seminiferous tubules, enter short straight ducts, tubuli recti, that connect the open end of each seminiferous tubule to the rete testis, a system of labyrinthine spaces housed within the mediastinum testis. The spermatozoa leave the rete testis through 10 to 20 short tubules, the ductuli efferentes, which eventually fuse with the epididymis.

The vascular supply of each testis is derived from the testicular artery, which descends with the testis into the scrotum accompanying the ductus deferens (vas deferens).

The capillary beds of the testes are collected into several veins, the pampiniform plexus of veins, which are wrapped around the testicular artery.

Blood in the pampiniform plexus of veins is cooler than that in the testicular artery, reduces the temperature of the arterial blood, thus forming a countercurrent heat exchange system, keeping the temperature of the testes a few degrees lower (35˚ C), than that of the remainder of the body. At this cooler temperature spermatozoa develop normally; at body temperature, spermatozoa that develop are sterile.

THE SEMINIFEROUS TUBULE

The wall of the seminiferous tubule is composed of a slender connective tissue layer, the tunica propria, and a thick seminiferous epithelium, separated from each other by a well-developed basal lamina.

The seminiferous epithelium is several cell layers thick and is composed of two types of cells: Sertoli cells and spermatogenic cells. The latter cells are in various stages of maturation.

The lateral cell membranes of adjacent Sertoli cells form occluding junctions with each other, thus subdividing the lumen of the seminiferous tubule into basal and adluminal compartments. Thus, the zonulae occludentes of these cells establish a blood-testis barrier that isolates the adluminal compartment from connective tissue influences, thereby protecting the developing gametes from the immune system..

Sertoli cells function in: supporting the developing spermatogenic cells; establishing the blood-testis barrier; phagocytosis of cytoplas shed by developing spermatogenic cells; manufacturing the following substances: androgen binding protein (ABP), antimullerian hormone, inhibin, testicular transferrin, and a fructose-rich medium.

SPERMATOGENESIS

Most of the cells composing the thick seminiferous epithelium are spermatogenic cells in various stages of maturation. Some of these cells, spermatogonia, are located in the basal compartment, whereas most of the developing cells—primary spermatocytes, secondary spermatocytes, spermatids, and spermatozoa—occupy the adluminal compartment.

Spermatogonia are diploid cells that undergo mitotic division to form more spermatogonia as well as primary spermatocytes, which migrate from the basal into the adluminal compartment.

Primary spermatocytes enter the first meiotic division to form secondary spermatocytes, which undergo the second meiotic division to form haploid cells known as spermatids.

Spermatids are transformed into spermatozoa by shedding of much of their cytoplasm, rearrangement of their organelles, and formation of flagella.

The maturation process is divided into three phases:

–Spermatocytogenesis: spermatogonia differentiate into primary spermatocytes

–Meiosis: reduction division whereby diploid primary spermatocytes reduce their chromosome complement, forming haploid spermatids

–Spermiogenesis: transformation of spermatids into spermatozoa (sperm)

SPERMATOZOON

Spermatids discard much of their cytoplasm and form a flagellum to become transformed into spermatozoa, a process known as spermiogenesis.

The spermatozoa (sperm) are long cells (~65 μm), composed of a head, housing the nucleus, and a tail, which accounts for most of its length

The tail of the spermatozoon is subdivided into four regions: neck, middle piece, principal piece, and end piece. The plasmalemma of the head is continuous with the tail’s plasma membrane.

The neck (~5 μm long) connects the head to the remainder of the tail. It is composed of the cylindrical arrangement of the nine columns of the connecting piece that encircles the two centrioles, one of which is usually fragmented. The posterior aspects of the columnar densities are continuous with the nine outer dense fibers.

The middle piece (~5 μm long) is located between the neck and the principal piece. It is characterized by the presence of the mitochondrial sheath, which encircles the outer dense fibers and the centralmost axoneme. The middle piece stops at the annulus. Two of the nine outer dense fibers terminate at the annulus; the remaining seven continue into the principal piece.

The principal piece (~45 μm long) is the longest segment of the tail and extends from the annulus to the end piece. The axoneme of the principal piece is continuous with that of the middle piece. Surrounding the axoneme are the seven outer dense fibers that are continuous with those of the middle piece and are surrounded, in turn, by the fibrous sheath.

The end piece (~5 μm long) is composed of the central axoneme surrounded by plasmalemma. The axoneme is disorganized in the last 0.5 to 1.0 μm.

GENITAL DUCTS

Intratesticular Genital Ducts

The intratesticular genital ducts are the tubuli recti (straight tubules), the rete testis, and the ductuli efferentes. These ducts carry spermatozoa and liquid from the seminiferous tubules to the ductus epididymidis.

Most seminiferous tubules are in the form of loops, both ends of which join the rete testis by structures known as tubuli recti. These tubules are recognized by the gradual loss of spermatogenic cells, with an initial segment in which only Sertoli cells remain to form their walls, followed by a main segment consisting of cuboidal epithelium supported by a dense connective tissue sheath.

Tubuli recti empty into the rete testis, contained within the mediastinum, a thickening of the tunica albuginea. The rete testis is a highly anastomotic network of channels lined with cuboidal epithelium.

From the rete testis extend 10-20 ductuli efferentes. They have an epithelium composed of groups of nonciliated cuboidal cells alternating with ciliated cells that beat in the direction of the epididymis. This gives the epithelium a characteristic scalloped appearance. The nonciliated cells absorb much of the fluid secreted by the seminiferous tubules. The activity of ciliated cells and fluid absorption create a fluid flow that sweeps spermatozoa toward the epididymis. A thin layer of circularly oriented smooth muscle cells is seen outside the basal lamina of the epithelium. The ductuli efferentes gradually fuse to form the ductus epididymidis of the epididymis.

Excretory (extra testicular) Genital Ducts

Excretory genital ducts transport the spermatozoa produced in the testis toward the penile meatus. These ducts are the ductus epididymidis, the ductus (vas) deferens, and the urethra.

The ductus epididymidis is a single highly coiled tube about 4-6 m in length. Together with surrounding connective tissue and blood vessels, this long canal forms the body and tail of the epididymis. It is lined with pseudostratified columnar epithelium composed of rounded basal cells and columnar cells. These cells are supported on a basal lamina surrounded by smooth muscle cells, whose peristaltic contractions help to move the sperm along the duct, and by loose connective tissue rich in blood capillaries. Their surface is covered by long, branched, irregular microvilli called stereocilia. The epithelium of the ductus epididymidis participates in the uptake and digestion of residual bodies that are eliminated during spermatogenesis.

From the epididymis the ductus (vas) deferens, a straight tube with a thick, muscular wall, continues toward the prostatic urethra and empties into it. It is characterized by a narrow lumen and a mucosa with longitudinal folds, covered along most of its extent by pseudostratified columnar epithelium with stereocilia. The lamina propria is rich in elastic fibers, and the thick muscular layer consists of longitudinal inner and outer layers separated by a circular layer. The abundant smooth muscle produces strong peristaltic contractions that participate in the expulsion of the spermatozoa during ejaculation.

The ductus deferens forms part of the spermatic cord, which includes the testicular artery, the pampiniform plexus, and nerves. Before it enters the prostate, the ductus deferens dilates, forming a region called the ampulla. In this area, the epithelium becomes thicker and extensively folded. At the final portion of the ampulla, the seminal vesicles join the duct. From there on, the ductus deferens enters the prostate, opening into the prostatic urethra. The segment entering the prostate is called the ejaculatory duct. The mucous layer of the ductus deferens continues through the ampulla into the ejaculatory duct, but the muscle layer ends after the ampulla.

MALE ACCESORY GENITAL GLANDS

The accessory genital glands produce secretions that are essential for the reproductive function in men. The accessory genital glands are the seminal vesicles, the prostate, and the bulbourethral glands.


The Seminal Vesicles

The seminal vesicles consist of two highly tortuous tubes about 15 cm in length. When the organ is sectioned, the same tube is observed in different orientations. It has a folded mucosa that is lined with cuboidal or pseudostratified columnar epithelium rich in secretory granules. These granules have ultrastructural characteristics similar to those found in protein-synthesizing cells. The lamina propria of the seminal vesicles is rich in elastic fibers and surrounded by a thin layer of smooth muscle. The seminal vesicles are not reservoirs for spermatozoa. They are glands that produce a viscid, yellowish secretion that contains spermatozoa-activating substances such as carbohydrates, citrate, inositol, prostaglandins, and several proteins. The carbohydrates, of which fructose is the most abundant, are the source of energy for sperm motility. Seventy percent of human ejaculate originates in the seminal vesicles. The height of the epithelial cells of the seminal vesicles and the degree of activity of the secretory processes are dependent on testosterone levels.

The Prostate Gland

The prostate gland, the largest of the accessory glands, is pierced by the urethra and the ejaculatory ducts. The slender capsule of the gland is composed of a richly vascularized, dense irregular collagenous connective tissue interspersed with smooth muscle cells. The connective tissue stroma of the gland is derived from the capsule and is, therefore, also enriched by smooth muscle fibers in addition to their normal connective tissue cells.

The prostate gland, a conglomeration of 30 to 50 individual compound tubuloalveolar glands, is arranged in three discrete, concentric layers mucosal, submucosal, and main.

The mucosal glands are closest to the urethra and thus are the shortest of the glands. The submucosal glands are peripheral to the mucosal glands and are consequently larger than the mucosal glands. The largest and most numerous of the glands are the peripheralmost main glands, which compose the bulk of the prostate.

The lumina of the tubuloalveolar glands frequently house round to oval prostatic concretions (corpora amylacea), composed of calcified glycoproteins, whose numbers increase with a person’s age.

The prostatic secretion constitutes a part of semen. It is a serous, white fluid rich in lipids, proteolytic enzymes, acid phosphatase, fibrinolysin, and citric acid. The formation, synthesis, and release of the prostatic secretions are regulated by dihydrotestosterone, the active form of testosterone.

The Bulbourethral Glands

The bulbourethral glands (Cowper's glands), 3-5 mm in diameter, are proximal to the membranous portion of the urethra and empty into it. They are tubuloalveolar glands lined with mucus-secreting simple cuboidal epithelium. Skeletal and smooth muscle cells are present in the septa that divide each gland into lobes. The secreted mucus is clear and acts as a lubricant.

PENIS

The penis is composed of three columns of erectile tissue, each enclosed by its own dense, fibrous connective tissue capsule, the tunica albuginea.

Two of the columns of erectile tissue, the corpora cavernosa, are positioned dorsally; their tunicae albugineae are discontinuous in places, permitting communication between their erectile tissues. The third column of erectile tissue, the corpus spongiosum, is positioned ventrally. Because the corpus spongiosum houses the penile portion of the urethra, it is also called the corpus cavernosum urethrae. The corpus spongiosum ends distally in an enlarged, bulbous portion, the glans penis (head of the penis). The tip of the glans penis is pierced by the end of the urethra as a vertical slit.

The three corpora are surrounded by a common loose connective tissue sheath, but no hypodermis, and are covered by thin skin. Skin continues distal to the glans penis to form a retractable sheath, the prepuce. When an individual is circumcised, it is the prepuce that is removed.

Erectile tissue of the penis contains numerous variably shaped, endothelially lined spaces. The vascular spaces of the corpora cavernosa are larger centrally and smaller peripherally, near the tunica albuginea. However, the vascular spaces of the corpus spongiosum are similar in size throughout its extent.

Refferences :

• Gartner, L.P. and Hiatt, J.L. Concise Histology. 2011

• Color Textbook Histology, third edition, leslie P. Gartner
• Basic Histology, tenth edition, L. Carlos Junqueira,2003
• Histology and Cell Biology, second edition,2007
• Elsevier’s Integrated Histology,2007

Read More [...]

Posted in 2012 , lecture , male genital system , materi kuliah