～～Simple Question on Menstruation～～

To understand the mechanism of menstruation, you must first know what hormonal control is. Study the following steps.
(1)When gonadotropin releasing hormone, GnRH, is released by the hypothalamus, it stimulates the anterior pituitary gland to secrete follicle stimulating hormone, FSH. (2) FSH acts on the receptors of the primoridal follicle, causing the follicle in ovaries to develop. (3)The granusola cell of the follicle will then release oestrogen. (3a) In the first half period of the menstruation, the level of the oestrogen rises rapidly corresponding to the growth of the follicle. (3b) When the time comes to the middle period of the menstruation, the level of the oestrogen reaches its max. value[day 14] and triggers the release of luteinizing hormone, LH [also nearly day 14]. (4) When the level of both FSH and LH are at surge (頂峰),[day 14]ovulation occurs. Egg cell is released from ripen graafian follicle to fallopian tube. The remaining part of graafian follice becomes corpus luteum. (5) The release of LH ,due to the presence of corpus luteum, triggers the release of progesterone [from 17 day to 27 day] causes the endometrium (i.e. uterine lining)to grow and thickening continuously. During the 17 days to 27 days, progesterone level is still high,not dropping.(6) When there is no fertilization occurs, the level of progesterone drops [at day 28]. Without progestrogen, the endometrium can't be thickening further and thus slough off(脫落)[day 28]. (7) Finally menstruation occurs.
So, will the egg pass out of the body together with the c ollapsed uterine lining at the same time?Ans: No, they are not occurring the same period(time).For the formation of egg cell, it occurs in day14 , while for the endometrium to slough off, it occurs at day 28. The days are not synchorized(同步). Besides, when an egg cell comes from the ovaries through the fallopian tube, the level of LH starts to drop. But the level of progestrogen is still high. Hence the endometrium won't start to slough off at this moment due to the high level of progesterone.
If not, will the egg pass out of the body before or after the uterine lining passes out of the body?Ans: The answer should be first egg cell comes from the ripen graafian follicle. If no fertilization occurs, (NO, HCG presence), the level of progesterone drops and endometrium slough off and passes out of the body
HCG = human chorionic gonadotropin
I hope you will find them helpful.

may not ar...

because the egg may be destroyed and absorbed by the organ.

Both of before and after are possible

the egg pass out of the body together with the collapsed uterine lining at the same time