P granules function in germ line formation of Caenorhabditis elegans

C.elegans is a free living nematode about 1mm in length and is found in temperate soils. Research into the molecular and developmental biology of the organism begun in 1974 by Sydney Brenner, and it has been used extensively as a model organism since.

This organism is used as an example because the same pattern of cell divisions is evident in all individuals, and a lineage tree can be constructed that traces the descent of each somatic cell.

The single celled zygote, after fertilization is called Po and is an ellipsoidal cell.

Po divides asymmetrically across the long axis resulting in a larger AB cell and smaller P₁ cell.

The AB cell will divide to eventually form the skin (hypoderm), neurons and the nervous system.

The P₁ cell will eventually form the muscles, digestive system and germ line.

P granules are incorporated exclusively in P1 at the first division. When P₁ divides, asymmetrically, the P granules are found in the progeny P2 cells (till Px). The Px cell with these granules becomes the germ line, while all other cells are somatic.

The asymmetrical distribution of p granules is microfilament dependant.