The Sperm and the Egg
The miracle of life is at the same time amazingly complex and alarmingly simple. It all starts with the act of love. During intercourse, a man can ejaculate up to 500 million sperm inside a woman’s vagina. Each sperm carries the father’s genetic code (or DNA). A man’s testes are constantly at work, churning out over 1000 sperm every second (Rathus, 2011). The quality of the sperm depends on the man’s age, lifestyle, his diet, and more. It’s a very slow, very long, very exhausting journey for the sperm as they are the smallest cell in the body – they can only travel about 1/10 of an inch per minute, wiggling their tails to propel them forward millimeter by millimeter. The journey is also dangerous. It was always somewhat of a mystery how the sperm would find its way to the egg, but according to the text, recently researchers have discovered that “sperm cells possess the same kind of receptors that the nose uses to sense odors” (Rathus, 2011). So sperm may actually find their way to an egg cell by tracking its scent. From the vagina they pass through the cervix, and up into the uterus, an on into the fallopian tubes where the woman’s egg (the largest cell in the body) is waiting in only one of them. Each month a woman’s ovaries release one egg that contains her own genetic code. She made these eggs while she was still a fetus herself, and they’ve been kept in storage until puberty, when her body was ready to make a baby. But it takes two to tango – so to speak. The sperm fight their way through the hostile environment, and many of them don’t survive. Others get lost. The slow and weak give up and go off track or get trapped. Strong currents fight the sperm at every moment, and the follicles on the uterine wall grab ahold of the sperm and hold them back. For the lucky and very few who manage to find their way to the elusive egg, the last battle commences mercilessly. The first sperm to burrow its head...
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