Describe the regulation of the ovarian and uterine cycles

Question

What will be an ideal response?

Answer 1

Ovarian cycle has two phases. Follicular phase—operates first half of cycle, granulosa cells of some primary follicles proliferate, oocyte inside each follicle enlarges, theca cells in follicle secrete increased amounts of estrogen, estrogen targets the uterus endometrium to repair itself and proliferate. Luteal phase—lasts 14 days of ovarian cycle, old follicular cells undergo structural transformation to form corpus luteum, corpus luteum produces progesterone and becomes fully functional within four days after ovulation, continues to increase in size for another four or five days. If released ovum is not fertilized and does not implant, corpus luteum degenerates within about 14 days after its formation. If fertilization occurs, fetal tissue produces hormone HcG (human chorionic gonadotropin), which prevents the corpus luteum from degenerating. Uterine cycle reflects hormonal changes during ovarian cycle.
Uterine cycle has three phases: menstrual phase—characterized by discharge of blood and endometrial debris from vagina, coincides with end of ovarian luteal phase (degradation of corpus luteum) and onset of follicular phase. Proliferative phase—begins concurrent with last portion of ovarian follicular phase, endometrium starts to repair itself and proliferate under influence of estrogen from newly growing follicles. Secretory or progestational phase—uterus enters this phase after ovulation when corpus luteum is formed, corpus luteum secretes large amounts of progesterone and estrogen. Converts endometrium to highly vascularized, glycogen-filled tissue; endometrial glands actively secrete glycogen