Menstruation is the periodic vaginal discharge of endometrial tissues and blood that are shed from the lining of a woman's uterus. Also denoted as periods, menstruation is part of the menstrual cycle which prepares a woman's body for fertility every month. It is a significant indicator of reproductive and general female infertility health, while other health issues may limit this capacity.
The menstrual cycle can be divided into the stages of the follicular phase (14 days during which the proliferative phase occurs), ovulation, luteal phase (14 days during which the secretory phase occurs), and menstruation.
Phases of menstrual cycle
Menstruation:
If the ovum does not implant, the corpus luteum degenerates, and the progesterone levels decrease resulting in the sloughing off of the endometrium lining (Menstruation).
Follicular Phase:
During the follicular phase, the release of FSH (follicle-stimulating hormone) from the pituitary results in the development of a primary ovarian follicle. This primary ovarian follicle produces estrogen which causes the uterine lining to proliferate (proliferative phase).
Ovulation:
During the middle of the menstrual cycle (14 days), an increase in LH (LH spike) results because of the estrogen produced during the proliferative phase. This LH spike causes ovulation (release of ovum from the follicle) to occur.
Luteal Phase:
Ovulation is followed by the luteal phase, during which the remnants of the follicle (left behind after ovulation of the ovum) develop into the corpus luteum.
During this stage, the endometrium solidifies more and the uterine glands initiate to produce their secretions of life-supporting substances for the nurture of a fertilized egg. If the egg becomes fertilized by sperm and then attaches itself to the uterine lining, the corpus luteum secretion now becomes controlled by a different hormone, (HCG), manufactured by the placenta. If the egg is not inseminated, the secretions of the corpus luteum are still precise by LH.
