 2-cells embryo |
Development begins at the point of fertilization – the meeting of a spermatoziode and an ovule. After the second splitting of meiosis and the fusion of the nuceus, the fertilized ovule becomes a zigote or an egg cell… After fertilization, the egg divides and the marvels of differeciation begin. During this period the egg moves slowly up the fallopian tube. |
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The first division of the zygote requires 24 hours. Each new cell then divides in turn, but there is no growth within each cell. On the fourth day (32 cells) the egg becomes a morula and finally reaches the uterus. |
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The cell division process continues, the egg is transformed and duly becomes a blastocyst, containing an embryonic bud from which the embryon develops. The blastocyst settles down in the uterine muceus. |
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The embryonic stage lasts two months, during which the various and different structures appear. At the end of the eight week all the systems are in place. The embryo has grown from 0.1mm to 3cm. The heart beat is visible as of the 21st day. By the fourth week, the head and limbs are recognisable. |
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At two months the embryo weighs about 1 gm, its heart is totally formed, and it becomes known as a foetus. By the end of the third month, all the organs are in place and they are fully formed by the fifth month. |
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As of the fifth month, and the beginning of the brain development, the movements of the fśtus become more and more precise. |
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From six months the fśtus is viable and a premature birth is feasible from this point onwards. |
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At nine months we have a newborn.
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