Summative question on endocrinology of puberty, based on what is taught at Keele, though questions and answers have been written by me myself
My time and effort has gone into this and that is reflected in price.
Good if your looking for some active recall.
1. Using the hypothalamus-anterior pituitary gonad axis, describe how endocrine ac-
tivity would respond to a increase in Oestrogen production;
- high levels of oestrogen will stimulate a negetive feedback response
- The hypothalamus will release less GnRh
- So less FSH and LH will be produced
- So less oestrogen will be made
- Unless its in the pre-ovulation phase in whihc high levels of oestrogen has a positive
feedback affect leading to production of LH and more oestrogen.
2. What is the role of the SRY gene on the Y chromosome (2m)
- initiates the differentiation of cells in the genital ridge primordial to become pre-ser-
toli cells and start development of the testes.
3. Describe how endocrine activity is responsible in the development of primary sex-
ual characteristics (4m)
- at the gonadal primordial ridge XY chromosomes will start to express their SRY gene
- This will lead to differentiation of cells and production of pre-sertoli cells
- Pre-sertoli cells cause development of testes,
- Leydig cells in testes start to produce testosterone
- Sertoli cells start to produce MIH
- Testosterone contributes to products of male external genitalia and degeneration of
female external genitalia via Dihydrotestosterone
- Testosterone also causes the mesonephri ducts to form which contribute to male in-
ternal genitalia
- MIH produced by Sertoli cells stops mullerian tubes (female internal genitalia from
forming)
4. Explain how the hypothalamus initiates the onset of puberty in a male using hypo-
thalamus anterior pituitary gonadal axis. (2m)
- Inhibition of GABA stops it inhibition of GnRh neurones in the hypothalamus
- Leads to increase in pulsate secretions of GnRh form the hypothalamus
- This leads to anterior pituitary releasing LH and FSH
- FSH stimulates spermatogenesis in Sertoli cells
- LH stimulates production of testosterone in leydig cells which leads to production of
DHT and secondary sexual characteristic
5. Describe the process of spermatogenesis
-in the periphery of the seminiferous tubules are type A and TypeB spermatogonium
-type A spermatogonium and type B constantly proliferating however type A stay in
the basal compartment of the seminiferous tubules and replenish the supply and type
B migrate to the adluminal compartment of the tubule
- in the adluminal compartment type B spermatogonium become primary spermato-
cytes
- Primary spermatocutes undergo meiosis I to form secondary spermatocytes
- Secondary spermatocytes undergo meiosis II to form spermatids
- Spermatids mature in the epididymis to form spermatozoon A mature sperm.
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