Moment of fertilization
The bottom left shows the edge of the female egg, about 50,000 times enlarged. (The egg can vary considerably in size, but, despite its small size, it is the largest cell of the body.) The figure also shows three spermatozoa enlarged at the same scale. The egg cell has just been fertilized by the topmost sperm cell. As soon as it passes inside, the outer wall of the egg is compacted, not missing anything more.
Until the eighth week after conception, male and female fruits look exactly the same. A week later - when the fetus is only 3 cm long and weighs 2 g - the external membrane disappears in the genitals of the female fetus, opening the entrance to the primitive vagina. At the same time, in the male fetus, one edge of the genital folds begins to lengthen, turning into a rudimentary penis. By the 11th week, contrasting forms of the external genitalia are outlined.
Date: 15.10.2018, 17:49 / Views: 41142
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