The second sex
It is well known today that the sex of the offspring depends on the chromosomal composition at the time of fertilization. Depending on the species involved, either male or female gametes are responsible for this result. In mammals, it's the sperm that does this. They produce an equal number of sperm, one with an X chromosome (which the eggs all contain) and one with a y chromosome (which the eggs do not). In addition to the X and y chromosomes, the egg and sperm contain an equal number of chromosomes. It is clear that when sperm and egg are fertilized, the fertilized egg contains two complete sets of chromosomes, which constitute the quantitative characteristics of the species-such as 48 chromosomes in human beings. If fertilization is accomplished by a single sperm with an X chromosome, the fertilized egg will contain two X chromosomes and will develop into a female (XX). If the egg is fertilized by a sperm with a Y chromosome, the fertilized egg will have only one X chromosome and will develop into a male (XY). The opposite is true for birds and butterflies, but the principle of determining their sex is still the same. The egg containing X or y determines the sex of the offspring. In heredity,Carbon in Pulp, Mendel's law States that the parents are equally protective and that the genes contained in the chromosomes are equally transmitted to the egg and sperm. Here we should pay special attention to. Neither gamete can be regarded as superior to the other; once United, both lose their individuality in the zygote. There are two common hypotheses (at least in the basic biological sense) that are demonstrably false. The first hypothesis, the female passivity, has been disproved by the fact that new life originates from the union of two gametes; the spark of life is not the exclusive property of one party. The nucleus of the ovum is the center of life activity strictly symmetrical to the nucleus of the sperm. The second false hypothesis,gold shaking table, contrary to the first, does not seem to prevent the coexistence of the two gametes. This hypothesis generally holds that the female origin guarantees the perpetuation of the species, while the male origin has a fleeting nature. In effect, the embryo perpetuates not only the mother's but also the father's germplasm, passing them on together to offspring in either male or female form. It can be said that this is a hermaphrodite germplasm, which lives longer than male or female individuals, and the offspring of these individuals are the embodiment of this germplasm whenever they are born. That said, we can turn our attention to the more minor differences between eggs and sperm, chrome washing machine ,Carbon in Pulp, which are quite interesting. The essential characteristic of the ovum is that it is provided as a means of nurturing and protecting the embryo; it stores the reserve of the embryo for the future establishment of tissue, and the yolk, which is inactive and inert. As a result, the eggs are heavy, generally spherical, and relatively large. The size of a bird's egg is obvious to all; a woman's egg is almost the size of a period (0. 132-0. 135 mm), but human sperm are much smaller (only 0. 04-0. So one cubic millimeter can hold 60,000 sperm. The sperm has a threadlike tail and a small flattened oval head containing chromosomes. No inert substance has crushed it, and it is full of vitality. Its entire structure is adapted for movement. The egg, which determines the future of the embryo, is static; it resides inside the female, or floats in the water outside, passively waiting to be fertilized. It was the male gamete that picked it up. The sperm is always a naked cell; the egg, depending on the species, may or may not be protected by a shell and a membrane. But in any case, as soon as the sperm meets the egg, it will press under it, sometimes shaking it vigorously, and finally get into the egg. At this time, its tail has fallen off, but its head is growing, becoming a male nucleus, and moving towards the nucleus of the egg. At this time, the egg will quickly form a membrane to prevent other sperm from entering. Starfish and other echinoderms are fertilized outside the body, so it's easy to watch the sperm circle the egg like a halo and launch a fierce attack on it. Competition here is an important phenomenon,sodium cyanide price, and it happens in most species. Sperm is much smaller than eggs, so the number of sperm produced is generally surprisingly large (the ratio of sperm to eggs is 200 million to one), so each egg has a large number of suitors. ore-magnetic-mining.com
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