Journey to ovulation begins during late luteal phase of prior menstrual
cycle, when certain 2-5 mm sized healthy follicles form a population, from
which dominant follicles is to be selected for next cycle This process is
called 'recruitment'. Usual number of such follicles may be 3-11, which goes
on decreasing with advancing age1.
During Day 1-5 of the menstrual cycle, a second process of 'follicular
selection' begins, when among all recruited follicles, certain growing
follicles of size 5-10 mm are selected, while rest of the follicles regress
or become atretic.
During Day 5-7 of the menstrual cycle, a process of 'dominance' begins, when
a certain follicle of 10 mm size takes the control and becomes dominant.
This also suppresses the growth of the rest of the selected follicles, and
in a way, is destined to ovulate. This follicle starts growing at rate of 2-
3 mm a day and reaches 17-27 mm size just prior to ovulation 2. One
important learning point in this regard is, "largest follicle on day 3 of
the cycle, may or may not be a dominant follicle in the end. Process of
dominance begins late, when suddenly a certain underdog follicle starts
growing faster and suppresses others to become dominant".
Almost nearing ovulation, rapid follicle growth takes place, and follicle
starts protruding from the ovarian cortex, attains a crenated border, and it
literally explodes to release the ovum, along with some antral fluid.
