Q. Select the incorrect statement :
(a) FSH Stimulates the Sertoli cells which help in spermiogenesis.
(b) LH triggers ovulation in ovary
(c) LH and FSH decrease gradually during the follicular phase
(d) LH triggers secretion of androgens from the Leydig cells
Solution :
Correct option :C During the first week after menses, FSH continues to increase, the follicles grow intensely. During this period, the follicles produce relatively small amounts of oestradiol and the circulating concentration of this steroid is relatively constant. During the second week, the follicles continue to grow and since they have increased their FSH receptors on the granulosa cells their aromatase actively transforms the thecal androgens into estrogens and the circulating oestradiol levels increase. This increase induces negative feedback on FSH which decreases slightly in the blood. The follicle which has the highest number of FSH receptors, the maximal aromatase activity and thus produces the highest concentration of oestradiol is named the dominant follicle and will be selected for ovulation, the others gradually degenerate during a process called atresia. Oestradiol continues to increase (particularly due to the activity of the dominant follicle) and reaches a peak about 72h before ovulation. These high levels of oestradiol induce by positive feedback, a brisk release of LH and FSH. Follicular rupture (ovulation) occurs about 36h after the LH peak. So, the incorrect statement is ‘LH and FSH decrease gradually during the follicular phase’