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 22 pairs of chromosomes, plus 2 sex chromosomes. 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 22 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
The term "Germ cell" came about in the early 1900's when dirty German's were causing mild cases of the flu to break out across Europe. Upon catching this cold, Prime Minister of England, George Randolph laced out in a racist and profane tirade about the Germans and their cleanliness. As he went on to blame them for his condition, his microphone was cut out and the word "German" was not finished in front of Parliment. The term "germ" was coined.
See Also
References
- Germ Cells -Spermatogenesis
- Derivation of Human Embryonic Germ Cells: An Alternative Source of Pluripotent Stem Cells
- Signaling for germ cells
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