Gametogenesis

As gametogenesis (also gamete, germ cell development ) the development of gametes or germ cells is called from the primordial germ cells.

First, in mammals wander the primordial germ cells formed in the embryonic phase from the intestine of the embryo into the Gonadenanlagen is forming. In humans, these are the female ovaries and the male testes. Then and therefore before birth gametogenesis begins.

Oogenesis and spermatogenesis

In multicellular organisms body cells carry all the chromosomes double in itself ( diploid set of chromosomes ). So after fertilization, the resulting cell also contains only two sets of chromosomes, the most important task of gametogenesis is the reduction to a single set of chromosomes ( haploid set of chromosomes ). For this purpose, a so-called reducing division meiosis is necessary to be in the gametes from gamont in several steps. In the female organism of spermatogenesis and spermiogenesis are formed by oogenesis, the eggs, the male organism within the sperm.

Gametopathie

As Gametopathie or germ cell damage congenital diseases or malformations are known to be caused by a disorder in the development of germ cells ( gametes). So there are defects that are already present in the egg or sperm cell leading to fertilization. This is either to defects which have occurred during the meiosis, or spontaneous mutations of genes. A congenital defect, its cause lies not in the gametes, but in the later development of the fetus, called foetopathy. Separates for example, a chromosome in meiosis not, it 's a follow- cell duplicated in the other not at all. In the latter case, the cell sequence is usually based. Fusing now at fertilization two gametes, one of which contains a double chromosome, this chromosome is present in triplicate in all subsequent cells, which can lead to serious disorders. Examples of Gametopathie by defective chromosome division are trisomy 21 (Down syndrome) and Turner syndrome.

Swell

  • Meyer's Encyclopedic Lexicon, Mannheim 1973.
  • H. Bayrhuber, U. Kull (eds.): Biology Schroedel Linder, 1989 in Hannover, 20th Edition, ISBN 3-507-02347-4
  • Genetics
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