Inhibin secreted by:
**Core Concept**
Inhibin is a protein hormone that plays a crucial role in regulating the pituitary-gonadal axis, particularly in suppressing follicle-stimulating hormone (FSH) secretion. It is involved in the feedback inhibition of FSH production, thereby controlling the reproductive cycle.
**Why the Correct Answer is Right**
Inhibin is secreted by the Sertoli cells in the testes and the granulosa cells in the ovaries. The inhibin hormone binds to the inhibin receptors on the surface of pituitary gonadotrophs, which activates a signaling cascade that ultimately leads to the suppression of FSH production. This feedback mechanism helps to regulate the balance of sex hormones and maintain reproductive homeostasis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the secretion of inhibin.
**Option B:** While granulosa cells do secrete inhibin, this option is incomplete and does not account for the testicular secretion of inhibin.
**Option C:** This option is incorrect as it does not specify the correct cell type responsible for inhibin secretion.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that inhibin plays a critical role in regulating the reproductive cycle, particularly in the feedback inhibition of FSH production. This knowledge is crucial in understanding the pathophysiology of various reproductive disorders.
**Correct Answer: B. Granulosa cells.**