Which statement correctly describes the secretory phase of the uterine (menstrual) cycle?

A. Follicle stimulating hormone stimulates proliferation of the endometrium

B. During this phase, the endometrium detaches and sheds

C. Progesterone stimulates the endometrium to prepare for implantation

D. Decreased progesterone levels cause the endometrial cells to die

The correct answer is C: "The secretory phase of the uterine (menstrual) cycle occurs when progesterone stimulates the endometrium to prepare it for implantation".

Explanation:

The luteal phase, also known as a secretory phase or postovulatory phase, has place immediately after ovulation, from 15th to 28th day, and it lasts until the end of the menstrual cycle when bleeding starts again.

During the secretory phase, the follicle in the ovary produces progesterone to keep preparing the uterus for a possible pregnancy. If there is no fecundation, estrogen and progesterone levels fall as the follicle reduces. When this happens, the endometrial is eliminated as menstruation and a new cycle begins.

If the ovule is fecundated, it occurs implantation and follicles continue to produce progesterone and estrogen in high amounts to sustain the endometrial until the placenta is formed.