Reproduction
For many years before a baby is conceived, the bodies of his parents have been getting ready for his conception. The mother's body has been producing egg cells (ova), and the father's sperm cells (spermatozoa) to fertilize them. Once an egg is fertilized, the baby needs a place to grow and develop; the mother's body has prepared such a place. When a girl reaches her teens her body begins to change, making it possible for her to produce and carry a baby. Her hips widen so that the pelvic cavity is large enough to hold a baby and allow it to pass through the birth canal. Her breasts enlarge so that after the baby is born, she can supply milk for him. Many changes are also going on insider her body. Each month one egg cell (ovum) is maturing and being released from one of her two ovaries. The ovaries are the storage place for undeveloped egg cells. An egg cell looks something like a hen's egg, except that it is the size of a pinpoint. It has a yellow center with a fluid around it. The outer covering or membrane is tough, but not as hard as a hen's egg shell. Each month the uterus, of womb, where the baby will grow, develops a special lining of blood vessels, which can nourish a baby. If an egg is not fertilized, it continues on it
The first sperm cell to reach the nucleus of the egg will live. All the rest will die in a few hours. mean that 92 chromosomes are crowded into the egg seems to disappear, and the double chromosomes start to pull apart. The dividing cell looks like a football with magnets at each end. Each "pole" or end seems to be attracting half of each chromosome pair. Forty- six chromosomes are drawn to one end and 46 are drawn to the other end. One major difference between sex cells and all other human tissue cells is that sex cells do not have the normal number of chromosomes, or heredity-determining factors. All other cells have 46 chromosomes. Egg cells and sperm cells are half complete, having only 23 chromosomes. When the two nuclei of the sex cells meet and unite, they form a complete cell with 46 chromosomes. This cell is the start of a new human being.
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Approximate Word count = 3317
Approximate Pages = 13 (250 words per page double spaced)
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