Popeâs Homily at Vespers on Eve of New Year âHoly Mother Church teaches us to end the year and also our days with an examination of conscience â¦ to be grateful and to ask for forgivenessâ December 31, 2014 ZENIT Staff Francis
Progesterone causes the endometrial glands to secrete, preparing the endometrium for blastocyst implantation. If the oocyte is fertilized, the corpus luteum enlarges to form a corpus luteum of pregnancy and increases hormone production. With pregnancy, chorionic gonadotropin, secreted by the trophoblast of the chorion, prevents degeneration of the corpus luteum.
During the luteal phase, the pituitary hormones FSH and LH cause the remaining parts of the dominant follicle to transform into the corpus luteum, which produces progesterone. The increased progesterone in the adrenals starts to induce the production of estrogen. The hormones produced by the corpus luteum also suppress production of the FSH and LH that the corpus luteum needs to maintain itself. Consequently, the level of FSH and LH fall quickly over time, and the corpus luteum subsequently atrophies. Falling levels of progesterone trigger menstruation and the beginning of the next cycle. From the time of ovulation until progesterone withdrawal has caused menstruation to begin, the process typically takes about two weeks, with 14 days considered normal.