Which of the following statements can be regarded as primary action of inhibin?
**Core Concept**
Inhibin is a protein complex that plays a crucial role in the regulation of the reproductive system, particularly in the feedback inhibition of the production of follicle-stimulating hormone (FSH) by the pituitary gland. It is produced by the Sertoli cells in the testes and by the granulosa cells in the ovaries.
**Why the Correct Answer is Right**
Inhibin primarily acts by inhibiting the production of FSH, which is essential for the growth and maturation of follicles in the ovaries and spermatogenesis in the testes. This action is mediated through the inhibin receptors, which are present on the surface of FSH-producing cells in the pituitary gland. The binding of inhibin to its receptors triggers a signaling cascade that ultimately leads to a decrease in FSH production. This feedback mechanism helps to regulate the reproductive cycle and maintain the balance between the production of sex hormones.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because inhibin does not primarily stimulate the production of FSH.
**Option B:** This option is incorrect because inhibin does not directly stimulate the production of testosterone or estrogen.
**Option C:** This option is incorrect because inhibin does not primarily stimulate the production of luteinizing hormone (LH), although it may have some indirect effects on LH production.
**Clinical Pearl / High-Yield Fact**
Inhibin is a useful marker for monitoring ovarian function and identifying cases of ovarian failure or premature ovarian insufficiency.
**Correct Answer: C. Inhibin primarily inhibits the production of FSH.**