Inhibin B is predominantly secreted by which gonadal cell type, and what is its specific feedback role in the male reproductive axis?

• A Leydig cells; inhibin B suppresses LH to provide negative feedback on testosterone production
• B Sertoli cells of the seminiferous tubules; inhibin B selectively suppresses FSH secretion from the anterior pituitary without significantly affecting LH ✓
• C Peritubular myoid cells; inhibin B paracrinally suppresses spermatogenesis when spermatozoan density is excessive
• D Sertoli cells; inhibin B suppresses both FSH and LH equally as part of a dual feedback mechanism

Explanation

Inhibin B is produced by Sertoli cells under FSH stimulation and serves as a specific negative feedback signal targeting FSH secretion at the anterior pituitary. Inhibin B binds activin receptor type II and signals via Smad2/3 to suppress FSH-beta subunit transcription. This is highly selective — inhibin B does NOT significantly suppress LH (which is regulated by testosterone feedback via GnRH pulse frequency changes). Inhibin B serum levels directly reflect Sertoli cell number and function; they are markedly reduced in azoospermia due to primary testicular failure (Sertoli cell only syndrome), making inhibin B a marker of spermatogenic function. Activin, the opposing TGF-β family member, stimulates FSH secretion.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.