Page 3 - 2.L.N-Reproductive phase of life in humans

Female Reproductive System

The menstrual cycle includes following steps:

 Maturation of eggs
 Release of matured eggs.
 Thickening of the wall of uterus
 Break down of thickened wall of uterus, if pregnancy does not occur.
 Embedding of fertilized egg in the uterine wall for further development, if
pregnancy occurs.

Sex determination in humans

 Human beings have 23 pairs of chromosomes in the nucleus of the cell. Out of
this, two chromosomes are sex chromosomes - called X and Y chromosomes.
 The female has two X chromosomes and male has one X and one Y
chromosome. The sperms and eggs have one set of sex chromosomes. Some
sperms have X chromosome and some have Y chromosome. All eggs have X
chromosome.
 If a sperm having X chromosome fuses with an egg having X chromosome the
child will be a girl. If a sperm having Y chromosome fuses with an egg having X
chromosome the child will be a boy.