In the male, LH acts on Leydig cells to stimulate testosterone synthesis. FSH acts on Sertoli cells and is essential for spermatogenesis. Which specific product of Sertoli cells serves as a paracrine signal from the seminiferous tubule to Leydig cells to amplify steroidogenesis, and which Sertoli cell product provides the direct hormonal feedback to the pituitary to suppress FSH?

• A IGF-1 from Sertoli cells amplifies Leydig steroidogenesis; inhibin B selectively suppresses pituitary FSH secretion ✓
• B Androgen-binding protein (ABP) amplifies Leydig cell function; inhibin B suppresses FSH
• C Insulin-like factor 3 (INSL3) amplifies Leydig cell function; activin suppresses FSH
• D AMH (anti-Müllerian hormone) from Sertoli cells suppresses Leydig steroidogenesis; activin stimulates FSH

Explanation

FSH stimulates Sertoli cells to produce IGF-1, which acts as a paracrine amplifier of LH-stimulated testosterone synthesis in adjacent Leydig cells — illustrating integrative cross-talk between FSH-Sertoli and LH-Leydig axes. Inhibin B, produced exclusively by Sertoli cells (FSH-stimulated), enters the portal/systemic circulation and selectively suppresses pituitary FSH secretion without significantly affecting LH, providing a gonad-specific feedback loop. This is why inhibin B is a clinical marker of spermatogenesis quality and testicular Sertoli cell function.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.