Since dimunculkannya cell theory in 1939, scientists knew that humans evolved from an egg that has been fertilized by a sperm. Consolidation of sperm with the egg known as the fertilization process, or conception. Sperm is collected in the vagina, then moves toward the uterus through the canal Uran eggs. While it is generally only one egg is produced, while the number of sperm deposited ranged between 200-300 million. Of
the many sperm, only one can fertilize the egg after a sperm can
penetrate the outer surface of the egg at fertilization, the egg
immediately develop a chemical barrier. This means that the egg is coated by the compounds
certain that millions of others do not participate sperm to fertilize the egg. When the sperm merges with the egg in the process of fertilization, the zygote formed has 46 chromosomes in its nucleus. Fertilization between egg and sperm occurs in the oviduct, and produce the zygote moves from the oviduct to the uterus. Over time, the zygote undergo cell division. After about 7 days, a collection of cells which are spherical zygote cleavage results will be embedded in the uterine wall. Before the zygote embedded, uterine wall thickening that had already been prepared to accept the zygote. Zygote in the uterus will grow for 9 months until the baby is born. For
humans and certain animals that embryonic development occurs in the
body of the female parent, there is a period before birth is called
gestation period or pregnancy. While
tissues, organs and body systems evolve, embryo in the uterus must
obtain food and oxygen, and remove metabolic waste materials. Embryos must also be protected. Study the following to be able to discover how the human embryo is protected to keep it alive.
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