Somatic cells

Definition

Any cell of a multicellular organism that contributes to body tissues and structures but is not part of the germ line; somatic cells divide by mitosis and do not transmit genetic information to offspring except in cases of somatic mutation or horizontal gene transfer. In arthropods, somatic cells form all cuticular, muscular, neural, and visceral tissues, while the distinction between somatic and germ-line cells becomes fixed early in embryogenesis through cytoplasmic determinants or asymmetric cell divisions.

Etymology

Greek sōma (body) + -ic, referring to cells that build the body rather than the reproductive lineage

Example

In Drosophila melanogaster, the pole cells segregate at the posterior pole of the early embryo and become the sole germ-line precursors; all remaining blastoderm cells become somatic cells that generate the larval epidermis, musculature, and nervous system but will never produce gametes.

Synonyms

• vegetal cells
• body cells

Related Terms

• germ cells
• gametes
• Mitosis
• Stem cells
• germ line
• somatic mutation
• pole cells
• Blastoderm

Usage Notes

The somatic/germ-line distinction is absolute in most animals but can blur in some arthropods: certain parasitoid wasps exhibit polyembryony where somatic cells of a single embryo proliferate and differentiate into both somatic tissues and secondary embryos, challenging the strict separation. In aphids and other parthenogenetic insects, somatic cells and germ cells may share more developmental plasticity than in sexually reproducing species. The term is never used for unicellular organisms or for the haploid products of meiosis.