Male Reproductive Flashcards
(41 cards)
What are the endocrine and exocrine functions of testes?
endocrine - produce steroid hormones (testosterone)
exocrine -produce spermatozoa
Testes is made of an outer layer of tunica vaginalis and a tunica albuginea. Describe their histological features and where they are.
Tunica vaginalis
- extension of abdominal peritoneum
- covers anterolateral surface
- consists of inner visceral layer (adheres to tunica albuginea) and outer parietal layer
- simple squamous epithelium
Tunica albuginea
-capsule of dense irregular CT
What is the mediastinum testis?
it is a thickening of the tunica albuginea on posterior surface. Vessels and ducts pass thru the mediastinum testis and it projects inward to form incomplete septa dividing testis into lobules.
What divides testis into lobules? What are the 2 components of testicular lobules?
The mediastinum testis (a thickening of tunica albuginea) forms incomplete septa to divide testis into lobules. The testicular lobules consist of semniferous tubules and interstitial tissue.
List 4 structures in testis
- semniferous tubules
- tubuli recti
- rete testis
- ductuli efferentes
The semniferous tubules are lined with stratified germinal epithelium composed of what 2 cell types? Also there’s a tunica propria with what 2 cells?
stratified germinal epithelium -> spermatogenic cells and sertoli cells
tunica propria -> myoid cells and fibroblasts
Spermatogenesis is making spermatozoa from spermatogonia. Where does it occur? How long does it take? Is there a hormone requirement?
Spermatogenesis forms spermatozoa which involves mitotic divison of spermatogonia, then meiotic division of spermatocytes. Then the spermatids will differentiate into spermatozoa (spermiogenesis).
This occurs in semniferous tubules (inward direction from basal lamina toward lumen) and takes 64 days and requires testosterone
Type A spermatogonia vs Type B spermatogonia
Type A –> stem cells
Type B –> progenitor cells that differentiate into primary spermatocytes
Explain spermatogenesis in terms of whether mitosis or meiosis is occurring and the chromomsome content.
type A spermatognia –> mitosis –> primary spermatocytes (2N)
primary spermatocytes (2N) –> first meiotic division/reduction division –> secondary spermatocytes (N)
secondary spermatocytes (N) –> second meiotic division –> spermatids (N)
What is the final step of spermatogenesis? Does it involve cell division? This process occurs when bound to which cells?
The final step is known as spermiogenesis (spermatids –> spermatozoa). it involves NO CELL DIVISION (just DIFFERENTIATION) and occurs while spermatids are bound to sertoli cells.
What is spermiation?
release of spermatozoa into lumen
What are sertoil cells histologically? What do they do for the spermatogenic cells. Are sertoli cells connected with each other?
Sertoli cells are tall columnar epithelial cells that sit on basal lamina and extend to lumen.
Their apical and lateral processes envelope spermatogenic cells. They have euchromatic nucleus with prominent nucleolus. They are tightly connected to neighboring sertoli cells via occluding/tight junctions
Briefly discuss the 4 main functions of sertoli cells.
1) support, protection, nutrition for germ cells
- mediate exchange of nutrients & metabolities
2) phagocytosis
- residual bodies
- degenerating spermatogenic cells
3) secretion
- testicular fluid
- ANDROGEN BINDING PROTEIN
- INHIBIN
4) blood-testis barrier
- protects sperm from blood-borne toxic agents
- isolates antigenic germ cells from immune system
The testis is composed of 2 components: the semniferous tubules which is the site of spermatogenesis and the interstitial tissue. This tissue is btw semniferous tubules. What does it contain?
1) nerves
2) blood vessels
3) lymphatics
4) CT: leydig cells, fibroblasts, macrophages, mast cells.
Leydig cells are found in the CT of intersitital tissue btw semniferous tubules of testes. Explain histological appearance of leydig cells and what is their function?
Leydig cells produce 95% of testosterone. It is active for 4 months in male fetuses then quiescent until puberty.
Histologically, they are large round/polygonal cells with central nuclei
Eosinophilic cyto rich in smooth ER and lipid droplets
cytoplasm may contain yellow-good lipofuscin which increase with age
The testis has semniferous tubules, tubuli recti, rete testis, and ductuli. The tubuli recti, rete testis and ductili efferentes are intratesticular ducts. Describe their function and histology
sperm will go from tubuli recti –> rete testis –> ductuli efferentes
tubuli recti (straight tubules) - these are short tubules w/in mediastinum that connects semniferous tubules with rete testis
rete testis - anastomatic network of channels in mediastinum
ductuli efferentes (efferent ductules) - 10-20 ducts that connect rete testis to epididymis
Does the tunica vaginalis (a serous sac made of simple squamous epithelium) cover all of the tunica albuginea?
No, it does not cover the thickening of the tunica albuginea which is known as the mediastinum testis
Explain the steps of spermiogenesis outlined below:
1) acrosome formation
2) flagellum formation
3) nuclear changes
4) change in orientation
5) spermiation
1) acrosome formation -granules accumulate in golgi and coalesce into a large acrosomal vesicle adj to nuclear envelope. Condensing nucleus forms acrosome which has hydrolytic enzymes that dissociate cells of corona radiata and digest zona pellucida
2) flagellum formation -centrioles migrate from next to nucleus to a position opposite the acrosome. One centriole initiates assembly of microtubules forming flagellum. mitochondria aggregate around proximal part of flagellum forming middle piece where swimming movement is generated
3) nuclear changes - nucleus condenses, elongates, and moves anteriorly displacing cytoplasm (very little cytoplasm is left)
4) change in orientation -halfway thru spermiogenesis, spermatid reorients itself so head points towards basal lamina and developing flagellum extends into lumen
5) residual body (excess cytoplasm) is released and phagocytosed by sertoli cells. spermatids are released from sertoli cells and from each other into lumen as spermatozoa (spermiation)
What cells secrete androgen binding protein? What is the effect of ABP?
sertoli cells secrete ABP which will concentrate testosterone in semniferous tubules
from ductulis efferentes, explain the order in which sperm will go.
semniferious tubules –> tubuli retes –> rete testis –> ductuli efferentes –> epididymis –> vas deferens –> ejaculatory ducts –> penile urethra
Epididymis has a head, body region (histologically similar) and a tail. Describe the epithelium that lines the epididymus and the 2 cells that it has.
epididymis is a highly coiled tube lined with pseudostratified columnar epithelium. It has basal cells (stem cells) and principal cells. Principal cells are tall columnar cells with stereocilia and basally located nuclei
describe the smooth muscle cells found in head, body, tail of epididymis.
head & body –> thin circular layer of smooth muscle (helps move sperm; rhythmic contractions)
tail –> inner and outer longitudinal muscles and circular muscles (expels sperm; few rhythmic contractions)
Briefly describe the 5 functions of epididymis
- maturation of sperm
- acquire motility
- addition of DECAPACITATION FACTOR - reabsorption of remaining testicular fluid
- phagocytosis of remaining residual bodies and degenerating sperm
- principal reservoir for mature sperm (in tail region)
- contraction of smooth muscle layers in tail expel sperm during ejaculation
Where does sperm acquire the ability to fertilize an egg?
in the ductus epididmyis, the sperm will acquire surface-associated decapacitation factor. Capacitation occurs in female reprod tract prior to fertilization
