Germ cell

A germ cell is part of the germline and is involved in the reproduction of organisms. Germ cells should not be confused with "germs" (pathogens). For example, the germ cells in male and female humans are the sperm and the eggs respectively.

Germ cells includes all stages of gametogenesis, i.e. gametogonia, gametocytes, gametids and gametes. By a narrower definition, the term germ cell can also just refer to gametes, which are produced by meiosis of the aforementioned germ cells, but this definition is less precise. Cells that are not part of the germline are somatic cells.

Ploidy
Normal human somatic cells are diploid, which means they contain 23 pairs of chromosomes, including one pair of sex chromosomes; an X from the mother, and an X or a Y from the father. If the sex chromosomes are XX then the organism is female and if they are XY then the organism is male. Human germ cells are normally haploid, which means they contain half the chromosomes of somatic cells, or 23 chromosomes and one sex chromosome. Thus when the germ cells unite in fertilization, the cell becomes diploid, and commences embryogenesis.

Origin
Primordial germ cells are predecessors of germ cells. They migrate to the gonadal ridge, where they form gametogonia, and thus start gametogenesis

In gene therapy
Genetic therapy, where new genetic material is introduced into an organism, usually confers new, genetic instructions for a cell and it's daughter cells, and the new genetic information dies with the organism. When the genetic material is put into a germ cell, the new genetic information (for better or worse) may be transfered to biological offspring.

Additional Resources

 * Germ Cells -Spermatogenesis
 * Derivation of Human Embryonic Germ Cells: An Alternative Source of Pluripotent Stem Cells
 * Signaling for germ cells

خلية عروسية Keimzelle Cellule germinale 生殖細胞 Гоноцит