Inhibin B is secreted by which cell type and has what primary endocrine effect?

• A Theca cells; inhibits LH secretion via long-loop negative feedback
• B Granulosa cells (in females) and Sertoli cells (in males); selectively inhibits FSH secretion from anterior pituitary without suppressing LH ✓
• C Leydig cells; inhibits both LH and FSH equally via hypothalamic GnRH suppression
• D Corpus luteum lutein cells; inhibits FSH and LH to prevent double ovulation in the luteal phase

Explanation

Inhibin B is a member of the TGF-beta superfamily heterodimeric peptide hormone. It is produced by granulosa cells of the developing follicles (in females, mainly in the follicular phase; serum inhibin B peaks at mid-follicular phase and reflects follicular reserve) and by Sertoli cells (in males). Inhibin B selectively suppresses FSH secretion from anterior pituitary gonadotrophs without significantly affecting LH secretion. This selective FSH suppression provides important negative feedback to regulate the number of follicles recruited each cycle. In males, low inhibin B in Sertoli cell failure leads to elevated FSH (as in Klinefelter syndrome). Inhibin A (from luteinised granulosa/corpus luteum) is more prominent in the luteal phase and early pregnancy (as part of the Down syndrome serum triple/quad test). Options B–D are incorrect cell types or incorrect hormone specificity.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.