Explain the phase of menstrual cycle which occurs after ovulation.

Answer: The phase after ovulation is the luteal (secretory or progestational) phase, from about day 15 to day 28 of a 28-day cycle.

1. After the Graafian follicle releases the ovum, the ruptured follicle, under the influence of LH, changes into a yellow endocrine body, the corpus luteum.
2. The corpus luteum secretes large amounts of progesterone and some estrogen.
3. Progesterone makes the endometrium thicker, more vascular and glandular; the uterine glands secrete nutritive fluid. The uterus is thus prepared for implantation of the embryo.
4. High progesterone inhibits the secretion of FSH and LH, so no new follicle develops.
5. If fertilisation occurs, the corpus luteum persists (maintained by hCG from the embryo) and menstruation stops.
6. If fertilisation does not occur, the corpus luteum degenerates into the corpus albicans; progesterone level falls, the endometrium breaks down and menstruation (the next cycle) begins.