Question

Luteinizing hormone is responsible for

• A. Ovulation and formation of corpus luteum
• B. Controlling activity of corpus luteum
• C. Development of mammary glands
• D. Growth of female reproductive organs

Answer 1

Answer: (A)

LH is secreted by anterior pituitary which inhibits secretion of FSH, stimulate maturation and rupture of Graafian follicle and release of ovum. LH also stimulates formation of corpus luteum (the luteal/secretory phase; days 15-28) from ovulated Graafian follicle which in turn secretes estrogens and progesterone. This makes option A correct. In absence of implantation, progesterone and estrogens exerts negative feedback control over the anterior pituitary’s secretion of LH and causes degeneration of corpus luteum in the ovary. The lower progesterone level, as caused by disintegration of corpus luteum, results in disintegration of endometrium thereby initiating the next menstrual cycle. Thus, corpus luteum activity is under regulation of estrogen and progesterone via negative feedback control. This makes option B incorrect. LTH (luteotropic hormone/prolactin) is secreted by anterior pituitary gland and targets mammary gland to stimulate breast development and milk production after baby birth; this makes option C incorrect. Estrogens serves to stimulate the growth of the uterus and the vagina, is necessary for egg maturation as well as for the development of the secondary sex characteristics in females. This makes option D incorrect. Correct answer is A.