A Description of the Various Stages of Prenatal Development.
Through intercourse sperm is released into the woman's vagina, then swims through the opening of her uterus and out through her fallopian tubes. This can take about five minutes to pass through the uterus and reach the tubes and then an additional 15 minutes to pass through the tubes and reach the ovaries. The egg breaks out of the shell of her ovary and is penetrated by the head of one sperm. Immediately the ovum creates a chemical or electrical charge to preventing other sperm from entering.
The story of a baby's life begins when a sperm fertilizes an egg. Within half an hour, the fertilized egg begins dividing at a fast rate while traveling down the fallopian tube to the uterus. The bunch of cells then implants itself into the wall of the uterus, where it will continue to develop and grow. Three weeks into this process the bundle of cells is now an embryo. A special layer of cells formed in the uterus will become the placenta and through which nutritive substances will be carried to the new organism and waste products carried away. Another layer of cells forms the amnion or water-sac, which will surround the developing embryo except at umbilical cord. The little heart begins to beat. By the fourth week you can recognize the head, and it has an undeveloped brain. By the second month of pregnancy the embryo grows from 4 inches to an additional 1 ½ inches. Bones and muscles begin to round out the form of body. Face and neck develops and begin to give an appearance of a human being. The forehead is very big because of development of brain. Also limb buds get longer, muscles and cartilage develop, and sex organs begin to form.
At the third month sex organs continues to grow. The male sex organ shows more and the female remaining more neutral. Stomach cells start to secrete fluid and the kidneys begin functioning, with urine gradually seeping into amniotic fluid.