Cell lineage denotes the developmental history of a tissue or organ from the fertilized embryo. Cell lineage can be studied by marking a cell (with fluorescent molecules or other traceable markers) and following its progeny after cell division. Some organisms such as C. elegans have a predetermined pattern of cell progeny and the adult male will always consist of 1031 cells, this is because cell division in C. elegans is genetically determined and known as eutely. This causes the cell lineage and cell fate to be highly correlated. Other organisms, such as humans, have variable lineages and somatic cell numbers.