The Reproductive
System of a woman
The
Menstrual Cycle
The
Hormones
The Reproductive
System of a Man
The Role
of Testosterone
The Sperm's
Odyssey in the Female Reproductive Tract
The Process
of Fertilisation
The Menstrual
Cycle
The aspect of the reproductive system
that women are most aware of is the menstrual period which they have every
month. The menstrual cycle is the time from the beginning of one period
to the beginning of the next one. Usually menstrual cycles last about 28-
35 days, though anywhere from 3 to 6 weeks is considered normal.
During the menstrual cycle, the uterus
gets ready for pregnancy. Under the influence of the hormones estrogen
and progesterone, its lining grows rich and thick to prepare for the fertilized
egg. If pregnancy doesn't occur, the uterus must get rid of this lining
so that it can grow a new one in the next cycle. The old lining passes
out of the uterus through the vagina as the menstrual flow.
The menstrual flow thus consists
of: the shed uterine lining; blood (this comes from the blood vessels which
are torn when the lining is shed); and the degenerated unfertilised egg.
If the menstrual flow is heavy, there
may sometimes be clots in it. Sometimes the uterine lining is shed as large
fragments - and these may sometimes looks like bits of pregnancy tissue
to some women, who think they are miscarrying.
