Expression of follicle-stimulating hormone receptor in human ovary

The gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), are key hormones in the regulation of ovarian function. The acquisition of FSH receptors during folliculogenesis is believed to be a key event in the subsequent development of the follicle. However, the binding and biochemical properties of the human FSH receptor are not well-characterized owing to the low abundance of these receptors and the limited availability of human tissue. The binding experiments show that, while the affinity of the FSH receptor does not change through the menstrual cycle, the total number of FSH receptors in the leading follicles increases by about two-fold at mid-follicular phase compared with those at other periods. Northern blot analysis was used to measure relative levels of FSH receptor mRNA, and in situ hybridization was used to localize FSH receptor transcripts. Northern blot analysis of human ovaries detected two transcripts (4.1 and 2.4 kb) for the FSH receptor. The FSH receptor mRNA was abundant in the preovulatory follicle, with expression decreased by about 50% in the corpus luteum. Using in situ hybridization, FSH receptor mRNA was found to be confined to the granulosa cells of developing follicles. A reverse transcription-polymerase chain reaction amplification was used to detect the expression of different isoforms of the FSH receptor mRNA in human corpus luteum and placenta.