BSI 2 Lecture 56: Male Reproductive Flashcards
Where is sperm produced?
Seminiferous tubules
What is the path of sperm from the seminiferous tubule?
Seminiferous tubule, epididymis, vas deferens, ejaculatory duct, urethra
What is the function of the prostrate, seminal vesicles, and bulbourethral?
To add their necessary secretions to increase viability of sperm
What is spermatogenesis?
The production of haploid sperm
In the embyro, what migrates into the testes and develops into spermatogonia where they wait until puberty to complete meiosis?
Primordial germ cells
What are the steps of spermatogenesis?
1) Leydig cells secrete testosterone to encourage the spermatogonia to enlarge and develop into primary spermatocytes (diploid)
2) The primary spermatocytes undergo meiotic division 1 to form secondary spermatocytes
3) The secondary spermatocytes undergo meiotic division 2 to form 4 haploid spermatids
4) Which will then develop and mature into sperm with the nurturing of Sertoli cells
How long is the process to make sperm?
74 days
Explain the different parts of the sperm and their function.
The head is the nucleus, which contains the haploid DNA, surrounded by a thing layer of cytoplasm and a cell membrane. Covering the anterior portion of the head is the acrosome, which contains lysosomal-like enzymes necessary for egg penetration. The mid-piece contains mainly mitochondria to provide energy for the tail. The tail is a long flagellum that allows the sperm to be motile
What hormones are needed for spermatogenesis?
1) Testosterone from Leydig cells
2) LH from anterior pituitary
3) FSH from anterior pituitary
4) Estrogens formed from testosterone
5) Growth Hormone
What is the function of LH in spermatogenesis?
It stimulates Leydig cells to release testosterone
What is the function of FSH in spermatogenesis?
It activates the Sertoli cells in the final stage when spermatids develop into sperm
What happens after sperm leave the seminiferous tubule?
They pass through the epididymis and mature
Where is sperm stored and how long does it stay viable?
In the epididymis and is viable for greater than a month
When do sperm become mobile and capable of fertilization?
After ejaculation when the Sertoli cells and epididymis secrete a fluid containing testosterone, estrogens, enzymes, and nutrients (capacitation).
Explain the control of secretion of FSH and LH
The hypothalamus releases GnRh which stimulates the anterior pituitary to release FSH and LH which act on the the gonads to secrete testosterone. Testosterone release will inhibit LH and the hypothalamus. While the gonads will activate inhibin which inhibits the hypothalamus and FSH
