Question

Select the correct match with respect to the phases of the menstrual cycle and the events that occur in them.

• A. Proliferative phase → Rapid regeneration of myometrium and maturation of Graafian follicle
• B. Secretory phase → development of corpus luteum and increased secretion of progesterone
• C. Menstruation → breakdown of myometrium because ovum is not fertilised
• D. Ovulation → LH and FSH attain a peak level and there is sharp fall in the secretion of progesterone

Answer 1

The correct option is B Secretory phase → development of corpus luteum and increased secretion of progesterone

Secretory phase of the uterine cycle coincides with the luteal phase of the ovarian cycle. Since the changes in the uterus are controlled by the hormones of the ovary, we would discuss them based on the changes occurring in the ovary. In the luteal phase, the ruptured Graafian follicle transforms into the corpus luteum under the influence of LH. The corpus luteum starts secreting progesterone which stimulates the uterine glands to produce mucus. Due to the absence of fertilisation, the corpus luteum degenerates after 2 weeks.
Proliferative phase of the uterine cycle coincides with the follicular phase of the ovarian cycle. The increase in levels of LH and FSH during this phase, leads to the development of ovarian follicles. The ovarian follicles start secreting estrogens. The estrogens enter the blood circulation and reach the uterus, where they stimulate the regeneration of the uterine wall. The endometrium becomes thicker by rapid cell multiplication and this is accompanied by an increase in the uterine glands and blood vessels.
In the menstrual phase of the uterine cycle, the endometrial lining of the uterus is shed. There is a rupture of blood vessels as well. Menstrual fluid carrying blood, tissue fluid, mucus, and the epithelial cells shed from the endometrium is lost through the vagina.
LH and FSH attain a peak just before ovulation, but there is no decline in the levels of progesterone during ovulation. The levels of progesterone remain the same as in the follicular phase.