Question

jim has just been diagnosed with testicular cancer. the tumor is composed of sertoli cells and they have begun to produce excessive amounts of inhibin. which of the following would be true?

multiple choice

fsh secretion would be selectively inhibited, but lh secretion would be normal.

spermatogenesis would be increased but testosterone secretion would be normal.

spermatogenesis would be increased because testosterone production would be above normal

gonadotropin - releasing hormone levels and spermatogenesis would increase above normal

both fsh and lh secretion would rise above normal levels

Explanation:

Inhibin specifically targets FSH (follicle - stimulating hormone) secretion. Sertoli cells produce inhibin. When there is excessive inhibin (due to the tumor), it acts on the anterior pituitary to selectively inhibit FSH secretion. LH (luteinizing hormone) is not directly affected by inhibin in this way. Testosterone secretion is mainly regulated by LH and Leydig cells, and since LH is normal, testosterone secretion remains normal. Spermatogenesis is influenced by FSH (among other factors). With FSH inhibited, spermatogenesis would not be increased. GnRH (gonadotropin - releasing hormone) is regulated by feedback from sex hormones and gonadotropins. Since FSH is inhibited (negative feedback on GnRH from FSH is reduced, but the main negative feedback on GnRH related to sex hormones is from testosterone for LH regulation). But the key is the specific action of inhibin on FSH.

Answer:

FSH secretion would be selectively inhibited, but LH secretion would be normal.