Endocrinology of Reproduction Lecture 8 part 2 // Cramberry: Create & study flash cards online

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Just list the cells of the testis spermatogonia, leydig cells, and sertoli cells

What are spermatogonia? These are the germ cells. They sperm producing stem cell line.

What are Leydig cells? There are the interstitial cells. They are stimulated by LH and synthesize/secrete T.

What are Sertoli cells? There are the follicular cells. They are stimulated by FSH (and to make ABP (Androgen Binding Protein) they also need T stimulation). These cells surround developing sperm. They are interconnected laterally by tight junctions, Sertoli cells form a "blood-testis barrier," thus protecting developing sperm cells. Sertoli cells contain abundant aromatase and can convert T to E2.

Testosterone Effects during Fetal Growth? During Fetal growth: induces the Wolffian ducts system directly; indirectly induces the prostate, urethra , penis, and scrotum through DHT by 5α-reductase-2

Testosterone Effects during Puberty? facial, axillary, and pubic hair. sebaceous glands [so far all by DHT] sperm production; larynx development; fat and muscle distribution; promotion and cessation of bone growth during puberty, but also stoppage of bone growth with increasing T post puberty (actually done by Estrogen converted from T by aromatase)

Testosterone Effects as an Adult? sex drive (libido in both sexes), muscle growth and maintenance (T is an anabolic steroid), increasing erythropoiesis, increase male pattern baldness, and increased colesterol.

Oligospermia defined as having less than 20 million sperm per ml. Caused by decreased GnRH, poor nutrition, or environmental factors.

Impotence (erectile dysfunction)? can be psychological or be due to anticholinergic drugs, nerve damage, or aging can inhibit arteriolar dilation, which occurs via the NO pathway. sildenifil (viagra) is a selective inhibitor of phosphodiesterase-5 (PDE5) which hydrolyzes the signaling molecule cGMP involved in Ca^2+ channel closure. Increase in cGMP => lower calcium concentration => smooth muscle relaxation => erection

Benign prostatic hyperplasia (BPH) and male pattern balding Since T must be converted to DHT in order for prostate growth and maintenance, specific inhibition of 5α-reductase-2 with finasteride (a T analogue) is used to treat BHP. Subjects thus treated also showed reversal of scalp hair loss. Finasteride can be used at a high dosage for prostatic hyperplasia (BPH) and a lower dosage for male pattern baldness.

In what pattern is GnRH released? It is released in a pluses and stimulates the gonadotropes of the anterior pituitary to secrete pulses of LH and FSH.

What does FSH stimulate in males? FSH stimulates the Sertoli cells to produce factors (ABP) that nurse the developing sperm cells and also produce inhibin B which inhibits further FSH release by the AP through negative feedback.

What does LH stimulate in males? What does it inhibit? LH stimulates the Leydig cells to produce testosterone and is required by developing sperm cells. Testosterone inhibits LH release by the anterior pituitary and also inhibits GnRH release by the hypothalamus (negative feedback)

What does 5α-reductase do in the body? It converts testosterone in non-gonadal target tissues to a more potent androgen, dihydrotestosterone (DHT).

What is the role of the enzyme aromatase in peripheral tissues in males? It converts androgens to estrogens. In the male 80-95% of E2 and E1 is formed by peripheral aromatization.