3 - Repro - Gamete development Flashcards
How do spermatogonia develop into sperm?
- Divide by mitosis into Type A light spermatogonium
- Mature into Type B cells
- Undergo 64 mitotic divisions to produce primary spermatocytes
- Divide via mitosis into secondary spermatocytes
- Divide via mitosis into spermatids
- Mature into sperm
Why are primary spermatocytes joined via cytoplasm bridges?
To allow simultaneous maturation
At what point do sperm become motile?
When reach epididymis
Approx how many sperm are released per ejaculation?
~ 350 million per ejaculation
What is the volume of a typical ejaculate?
~ 3-5ml
How many days does spermatogenesis take?
~ 70 days
How many spermatids can be yielded from one Type A ?
up to 256
Define spermatogenic cycle:
Time taken for the reappearance of the same stage of spermatogenesis within a given segment of seminiferous tubule ~ 16 days
Define spermatogenic wave:
The distance between the same stage in a seminiferous tubule. Waves move in corkscrew-like spirals towards the inner part of the lumen.
What is the role of the rete testis?
- Concentrates sperm
- Moves sperm towards the epididymis
What is the role of the epididymis?
- Stores sperm ~ 6-12 days
- Can phagocytose sperm
Approx how long is the epididymis (if stretched out)?
~ 4-6 m
Describe the epithelium of the epididymis:
Pseudostratified columnar epithelia with stereocilia
What is the function of the vas deferens?
- Propels sperm into the urethra for ejaculation
- Can store sperm for ~ weeks
- Can phagocytose sperm
What percentage of the ejaculate is secreted by the seminal vesicles?
~ 70%
Which nerve causes the peristaltic contraction of the smooth muscle of the prostate, vas deferens and seminal vesicles in ejaculation?
Sympathetic Hypogastric nerve (L1/2)
What are the contents of the secretion from the seminal vesicles?
- Amino acids
- Clotting factors
- Citrate
- Fructose
- Prostaglandins
Why do sperm use fructose rather than glucose?
So they do not have to compete with bacteria for glucose
Is the secretion from seminal vesicles acidic or alkaline?
Alkaline
Which male reproductive glands secrete alkaline fluid contributing to the ejaculate?
- Seminal vesicles
- Bulbourethral glands
Which male reproductive glands secrete acidic fluid contributing to the ejaculate?
Prostate
What percentage of the ejaculate is secreted by the prostate?
~ 25%
What percentage of the ejaculate is secreted by the bulbourethral glands?
~ 5%
What is the arterial supply to the prostate?
Inferior vesical artery (from internal iliac artery)
