Boy or girl
Of the 23 pairs of chromosomes in the cell of the body, 22 are always genuine pairs - that is, each chromosome in a pair is similar to the other. In women, the 23rd pair is identical: both chromosomes in this pair are called X chromosomes. But in men, these two chromosomes are not completely identical. One of them is Hkak and a woman, and the second (Y-chromosome) contains a small part of the genes of the X chromosome, and in addition, a set of genes that determine the male gender. The combination of XX occurs in women and produces them, the combination XY refers to men. When the female cell is divided for sexual reproduction, the resulting germ cell contains one chromosome from each of the 2? pairs, including the X chromosome.
When a male cell divides for sexual reproduction, the sexual cell contains one chromosome of 22 identical pairs, plus X or Y - but not both. This determines the sex of the unborn child. If fertilization is performed with a sperm cell with chromosome X, it forms a pair with the female X chromosome, and a girl is obtained. Accordingly, in the case of a sperm cell with a Y chromosome, a pair of XY is formed, which determines the male gender, a boy develops. Conception of boys occurs more often than girls, but boys more often die, even in the bud.Boys are more likely to be born dead than girls, and the more miscarriage occurs at an earlier gestational age, the higher the likelihood that this is male fetus. In a four-month pregnancy, two male miscarriages occur in one female; with a full term, this ratio is 1.5 to 1. As a result, the relative quantitative superiority of male fetuses over women decreases and in developed societies, by the full term of pregnancy, 105–106 boys per 100 girls.
- Fertilization leading to the birth of a boy
- (White arrows show other produced cells that are not involved in the process).
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