Male Reproductive Physiology Flashcards
What do the testes consist of?
- seminiferous tubules, where sperm are made
- interstitial tissue, between the tubules
- sperm transport duct system
What are the seminiferous tubules?
convoluted, hollow, fluid filled tubes that open at both ends and empty into the rete testis
What types of cells are in the seminiferous tubules?
sertoli cells
germ cells
What is on the basement membrane and lumen of the seminiferous epithelium?
basement membrane = spermatogonia (least differentiated)
lumen = spermatids (most differentiated)
What is the function of Sertoli cells?
serve to nurture the developing germ cells
extend from basement membrane to the lumen and surround the germ cells
Spermatogenesis consists of what?
- cellular proliferation by repeated mitotic division
- entry into meiosis with chromosome duplication, genetic recombination, and meiotic reduction divisions to give haploid spermatids
- terminal differentiation of spermatids to spermatozoa
Proliferation, meiosis, and differentiation are associated with which intermediate cell types?
proliferation = spermatogonia meiosis = spermatocytes differentiation = spermatids
How do type A spermatogonia turn into type B spermatogonia
after going through several mitotic divisions
Spermatogenic cycle
when spermatogonia clones enter meiosis, resting spermatogonia on basement membrane signaled to mitotically divide and new clones push previous clone closer to lumen
What happens in meiosis of spermatocytes?
Meiosis 1 - primary spermatocytes (2N4C) turn into secondary spermatocytes (1N2C)
Meiosis 2 - secondary spermatocytes (1N2C) are turned into spermatids (1N)
What happens in spermiogenesis?
long phase of terminal differentiation where the newly formed haploid round spermatid undergoes dramatic cellular changes to form the spermatozoa
Name some steps in spermiogenesis
- nucleus elongates and chromatin condenses
- Golgi apparatus produces small granules that coalesce to form acrosome
- pair of centrioles migrate to nucleus and bind to it
- axoneme elongates to form the core of the tail
- spermatid loses large amounts of cytoplasm to form the residual body
What is spermiation?
release of spermatid from its tether
released cell is now a spermatozoa
What is the function of apoptosis in spermatogenesis?
- keep number of germ cells to a level the Sertoli cells can support
- removal of defective sperm at quality check points
What are the functions of the Sertoli cells?
- organize clones of germ cells in seminiferous epithelium, support the cells, and ensure their timely release
- secrete controlling factors that regulate germ cell differentiation and maturation
- phagocytose degenerating cells
- produce androgen-binding protein that traps androgens for local and downstream use
- form tight junctions that form the blood-testis barrier
- major source of estrogen
What is the purpose of LH and FSH in males?
LH - acts on Leydig cells to increase testosterone secretion
FSH - acts on Sertoli cells and stimulates them in their supporting role, promotes seminiferous tubule growth, and androgen-binding protein production
Why is testosterone important for spermatogenesis?
testosterone helps maintain binding of Sertoli cells to developing sperm cell stages
What is the blood-testis barrier?
formed by tight junctions between adjacent SErtoli cells, divide the seminiferous epithelium into basal and adluminal compartments