In the female reproductive axis, inhibin A and inhibin B have distinct roles. During the luteal phase, which inhibin isoform is primarily secreted by the corpus luteum and feeds back to selectively suppress FSH?

• A Inhibin C
• B Inhibin B
• C Inhibin A ✓
• D Both inhibin A and inhibin B equally

Explanation

Inhibin C is primarily secreted by the dominant follicle and corpus luteum, selectively suppressing pituitary FSH during the luteal phase. Inhibin B is secreted by small antral follicles and granulosa cells during the follicular phase. The differential secretion pattern is used clinically: inhibin C rises in luteal phase, inhibin B is a marker of ovarian reserve. Inhibin A is not a major functional form in humans.

Reference: Ganong's Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.