A male patient with bilateral cryptorchidism has normal testosterone but very elevated FSH with azoospermia. Inhibin B is undetectable. Which cell type and physiological concept explains the selective FSH elevation?

• A Leydig cells produce inhibin B which suppresses FSH; their destruction elevates FSH
• B Sertoli cells produce inhibin B, which provides specific negative feedback to suppress FSH; absent spermatogenesis → absent inhibin B → elevated FSH with normal testosterone ✓
• C Loss of sperm production reduces luminal pressure in the seminiferous tubules, stimulating gonadotroph FSH production by a paracrine signal
• D Damaged Sertoli cells cannot convert testosterone to estradiol, removing estradiol-mediated FSH suppression

Explanation

Inhibin B is secreted exclusively by Sertoli cells in proportion to spermatogenic activity. Inhibin B selectively suppresses FSH secretion from anterior pituitary gonadotrophs without affecting LH. In cryptorchidism/azoospermia, Sertoli cells are dysfunctional and spermatogenesis fails — inhibin B is undetectable. Without inhibin B feedback, FSH rises markedly. Testosterone production by Leydig cells (dependent on LH, not FSH) remains intact since LH is normal, so testosterone is preserved. Leydig cells do not produce inhibin B (option A). Options C and D describe non-physiological mechanisms.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.