During the proliferative phase the pituitary gland increases production of FSH, which stimulates the developing follicles to mature and to produce several types of estrogen. Estrogen in turn causes the endometrium to thicken. Although several follicles begin to mature, usually only one reaches maturity; the other follicles degenerate. When the level of ovarian estrogen circulating in the bloodstream reaches a peak, the pituitary gland depresses the release of FSH and stimulates LH production.
Regardless of cycle length, ovulation occurs 14 days prior to the onset of menstruation. In response to the spurt of LH secreted by the pituitary gland, the mature follicle ruptures and the ovum is released.
secretory phase
the phase of the menstrual cycle during which the corpus luteum develops and secretes progesterone. blastocyst
Multicelled descendant of the united egg and sperm.