Follicular stimulating hormone receptors are present on:
**Core Concept**
Follicular stimulating hormone (FSH) is a gonadotropin hormone released by the anterior pituitary gland, playing a crucial role in the regulation of the reproductive cycle. FSH acts through its specific receptor, which is a G protein-coupled receptor (GPCR) that mediates its effects on the target cells.
**Why the Correct Answer is Right**
FSH receptors are primarily found on the surface of granulosa cells in the ovaries and Sertoli cells in the testes. These cells express FSH receptors, which upon binding with FSH, trigger a signaling cascade that ultimately leads to the stimulation of follicular growth in females and spermatogenesis in males. The FSH receptor is a member of the GPCR family, specifically belonging to the class II GPCR, which is characterized by the presence of a specific sequence of amino acids in the third intracellular loop.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect, as FSH receptors are not primarily found on the surface of Leydig cells in the testes.
**Option B:** Incorrect, as FSH receptors are not primarily found on the surface of adrenal cortical cells.
**Option C:** Incorrect, as FSH receptors are not primarily found on the surface of thyroid follicular cells.
**Clinical Pearl / High-Yield Fact**
FSH receptors are also found on the surface of some types of cancer cells, such as granulosa cell tumors, which can lead to an overproduction of estrogen. This is an important consideration in the diagnosis and treatment of these cancers.
**Correct Answer:** D.