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Chapter 9. Reproductive Physiology

A 34-year old-woman begins assisted fertility treatment to initiate ovulation. She is treated with an agent that acts via gonadotropin-releasing hormone (GnRH) receptors in the anterior pituitary. Which of the following treatments is most likely to be effective?

A GnRH agonist given in pulsatile doses

B GnRH agonist given continuously

C GnRH receptor blocker given in pulsatile doses

D GnRH receptor blocker given continuously

A. Pulsatile GnRH mimics the physiologic release pattern. Continuous dosing is ineffective because it downregulates pituitary gonadotropes.

A 58-year-old man complained of loss of libido and reduced muscle strength. Serum analysis showed reduced levels of testosterone. Reduced activity in which of the following hormone-target cell axes could account for his symptoms?

A Luteinizing hormone (LH) – Leydig cell

B Follicle-stimulating hormone (FSH) – Leydig cell

C LH – Sertoli cell

D FSH – Sertoli cell

E LH – spermatogonium

F FSH – spermatogonium

A. Leydig cells produce testosterone in response to LH.

A 17-year-old girl visited her physician because she had never had a menstrual period. Physical examination revealed a tall female with a short, blind-ended vagina and no palpable cervix. Ultrasound showed the absence of a uterus and no ovaries but the presence of undescended testes. Deficiency of which enzyme, hormone, or receptor is most likely to account for these findings?

A Androgen receptors

B Aromatase

C Estrogen receptors

D 21α-Hydroxylase

E Müllerian-inhibiting substance

F Progesterone

G 5α-Reductase

A. The patient has complete androgen insensitivity (testicular feminization) in which androgen-induced development of the mesonephric duct fails. Sertoli cells continue to secrete müllerian-inhibiting substance, so female internal reproductive organs also fail to develop.

A 57-year-old man was prescribed the phosphodiesterase type 5 inhibitor sildenafil to enhance sexual function. Which of the following effects will most likely occur after he has taken sildenafil?

A Penile erection in the absence of erotic stimulation

B Enhanced penile erection following normal erotic ...

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