Читать книгу Sister Lilian’s Pregnancy & Birth Companion - Lilian Paramor - Страница 10

Every cell in the human body has 46 chromosomes, arranged in 23 pairs, one of which determines gender. In the female egg cell, called an ovum, the sex chromosomes are designated as XX, in the male sperm, XY. X’s produce female babies and Y’s male babies. When an ovum is fertilised by a sperm cell, 23 chromosomes from each join. If the X from the sperm’s sex chromosome unites with the X from the ovum, the baby will be a girl; if the Y of the sperm cell joins the mother’s X, a boy will be born. In effect, the father determines the baby’s gender. The other chromosomes combine to carry all the hereditary features from both parents and their families.