Male Repro Physiology Flashcards
From which embryonic tissue do Sertoli cells originate?
Coelomic epithelial cells of gonadal ridge
From which embryonic tissue do spermatogonia originate?
Yolk sac
From which embryonic tissue do Leydig cells originate?
Mesenchyme of gonadal ridge
Which gonadotropin/sex hormone-like peptide is released from the hypothalamus?
GnRH
Which gonadotropins/sex hormones are released from the anterior pituitary?
Gonadotropins: - LH - FSH Hormone: - Prolactin
Which gonadotropins/sex hormones are released from the posterior pituitary?
- Oxytocin
- Vasopressin
Which enzyme converts testosterone to estrogen in the brain?
Aromatase
What are the 4 products of Sertoli cells?
1) Anti-Mullerian hormone / Mullerian inhibiting substance
2) Inhibin
3) Estrogen (converted from testosterone)
4) Androgen-binding protein (ABP)
______ is the main source of GnRH in males whereas _____ is the main source of GnRH in females.
Tonic center
Surge center
[Both belong to hypothalamus]
Which Sertoli cell products are involved in negative feedback of FSH?
Inhibin -> inhibits FSH directly
Estradiol (made from testosterone provided by Leydig cells) -> inhibits GnRH
Describe the negative feedback of testosterone
Testosterone inhibits both LH and GnRH
How does testosterone “defeminize” the hypothalamus?
Testosterone crosses BBB and, once in the brain, is converted to estradiol by aromatase
From where does alpha-fetoprotein come and what is its function?
Yolk sac; binds estradiol to prevent it from crossing the BBB (prevents defeminization of hypothalamus in females); also carries fatty acids
True or false: 5a reductase, which catalyzes conversion of testosterone into DHT, is found only in males.
False; it is also found in females. This is why women can develop masculine secondary sexual characteristics if given testosterone
List the steps in activation of Leydig Cells
1) LH binds receptor on membrane
2) cAMP produced
3) cAMP promotes transport of cholesterol into the mitochondria via StAR (Steroidogenic Acute Regulatory protein); RATE-LIMITING
4) Cholesterol -> prenenolone in the mitochondria
5) Pregnenolone -> Androstenedione -> Testosterone in SER
What are the three components of immune privilege in the testes?
1) Anatomical junctions - more complex than in other blood-tissue barriers
2) Physiological
- Specialized transport systems
- Immunosuppressive activity of testosterone
3) Immunological
- Blood testis barrier
- Immune cells of interstitial space
The two compartments of the testes are:
Basal compartment (spermatogonia only)
Adluminal compartment (everything else)
Describe the 3 phases of spermiogenesis
1) Cap Phase:
- Golgi body creates acrosomal cap
- Golgi migrates caudal to nucleus as acrosomal cap covers cranial nucleus
- Proximal centriole becomes implantation site for tail
- Distal centriole becomes axoneme
2) Acrosomal Phase:
- Nucleus elongates and acrosomal cap grows with it
3) Maturation phase
- Mitochondria migrate to midpiece
- Flagella forms in principle (most caudal) piece
How long is a cycle of the seminiferous epithelium (from spermatogonia to sperm)?
60 days (usually)
