THE START OF A NEW BABY

It takes just two cells coming together to start the development of a baby. One, the sperm, comes from the man, the other, the egg cell or ovum, is produced by the woman. A man starts to make sperm in his testes when he reaches puberty; girls are born with egg cells already in the ovaries. The first egg cell will be released when a girl’s monthly periods begin, probably about the age of 12 or 13. Another will be released every month thereafter, for 30 40 years.

For the sperm to get into a woman’s body, the penis has to be inserted into vagina. The penis is normally limp, but it becomes erect when a man is aroused, and can then be inserted into vagina. Millions of sperm leave the penis in a liquid called semen when the man ejaculates; then, using their tells, the sperm swim on up the fallopian tubes. If there is an egg cell there, one sperm may penetrate it; the rest will die. Conception occurs when sperm and ovum join to form a zygote.

·        A woman has two ovaries. An egg is normally released from one ovary one month, and from the other ovary the next month. If two eggs are released at the same time, twins may develop.

·        Sometimes a fertilized egg divides into two, and when this happens identical embryos will develop. Twins will be born.

·        When a sperm penetrates an ovum, the tail falls off and the head becomes bigger. When the sperm reaches the nucleus of the ovum  a zygote is formed, which grows as the cells divide.