During the follicular phase of a normal menstrual cycle ovarian changes occur which are due to pituitary secretions of

Options

A. oxytocin
B. LH only
C. FSH and LH
D. vasopressin

Answer

C

Explanation

The reproductive cycle is under hormonal regulation, gonadotropic hormones of the pituitary (anterior lobe) stimulate the ovaries to produce a mature egg. The pituitary and ovaries have a reciprocal effect upon each other. FSH (follicle stimulating hormone) from the pituitary elicits estrogen production from the developing follicle. When estrogen concentration reaches a certain blood level, it inhibits FSH production. At that time the egg is discharged and the cells lining the follicle come under the influence of another gonadotropin LH (luteinizing hormone) which influences the development of the corpus luteum. The corpus luteum produces the hormone progesterone which influences the wall of the uterus in preparation for implantation. As the concentration of progesterone rises, LH production is checked. If fertilization has occuned, the production of FSH is curtailed throughout the period of gestation through the production of estrogen by the placenta and ovary. If fertilization does not occur, the cycle begins anew.