menstrual cycle definition

menstrual cycle definition The average length of the menstrual cycle is 28 days.
Day one is by convention the first day of vaginal bleeding.
Themean duration of the menstrual flow is between
2–6 days with an average blood loss of 20–60 ml. Ovulation
generally occurs on day 14 (14 days before the
first day of the next vaginal bleeding). The normalmenstrual
cycle is divided into two segments. The follicular
phase (variable length: 10–14 days) and the luteal
phase (14 days). During the follicular phase hormonal
feedback promotes the development of a single dominant
follicle which is prepared for ovulation. The luteal
phase is the duration of time from ovulation to onset of
menses in which the endometrium is prepared for the
implantation of an embryo. If implantation with production
of HCG does not occur, menstrual flow begins
as a result of the shrinking of the corpus luteum resulting
in a fall of progesterone, the gestational hormone.