life of a sperm Flashcards
What are the 2 main products of the testis
Spermatazoa and hormones
What are the main compartments of the testis
Seminiferous tubules within which spermatogenesis occurs
vascularised stroma containing Leydig cells.
What is the role of androgens
Maintaining reproductive and sexual function
Where is testosterone synthesized and from what
synthesised from acetate and cholesterol by leydig cells
Some testosterone passes into the seminiferous tubules, what happens here
testosterone is converted into dihydrotestosterone by 5a reductase in Sertoli cells
How are the seminiferous tubules organised
Peripheral myeloid cells, then basement membrane, Sertoli and spermatogenic cells within the tubules.
Outline spermatogenesis in 3 acts
- mitotic proliferation to produce lots of cells
- meiotic division to generate genetic diversity
- cell modelling to package chromosomes for delivery to the oocyte
A spermatogonia—> resting primary spermatocytes—> haploid spermatids—>
What happens to the spermatids in the packaging phase
- acrosome forms for sperm to penetrate the oocyte
- cap region forms for sperm-oocyte fusion
- nucleus with packaged chromosomes
- midpiece with mitochondria for energy
- tail for forwarding propulsion
How long does spermatogenesis take
time for completion is 64 days
The final stages of maturation of spermatozoa occur elsewhere, where does this happen
Spermatozoa wash into the rete testis via the vasa efferentia, into the epididymis where fluid is absorbed and sperm is concentrated.
what are the cellular components of semen and where do they come from.
spermatozoa, epithelial cells from the tract, spermatogenic cells, leucocytes- risk of HIV etc.
Spermatazoa mixed with secretions from seminiferous tubules, epididymis, prostate etc.
What is the role of the fluid components of semen
provide a fluid vehicle for spermatozoa,
nutrition (fructose)
buffer (protect against vaginal acidity)
antioxidants (ascorbic acid, hypotaurine)
How does the endocervix aid sperm
Protection from the hostile vagina, and from being phagocytosed.
supplementation of energy requirements
sperm selection by differential motility and morphology
