Cell lineage  Cell lineage denotes the developmental history of a tissue or organ from the fertilized embryo. This is based on the tracking of an organism's cellular ancestry due to the cell divisions and relocation as time progresses, this starts with the originator cells and finishing with a mature cell that can no longer divide.  this type of 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. As one of the first pioneers of cell lineage, in the 1960s Dr. Sydney Brennerfirst began observing cell differentiation and succession in the nematode "Caenorhabditis elegans". Brenner chose this organism due to its transparent body, quick reproduction, ease of access, and small size which made it ideal for following cell lineage under a microscope. By 1976, Dr. Brenner and his associate, Dr. John Sulston, had identified part of the cell lineage in the developing nervous system of "C. elegans". Recurring results showed that the nematode was eutelic(each individual experiences the same differentiation pathways). This research led to the initial observations of programmed cell death, or apoptosis. After mapping various sections of the "C. elegans"' cell lineage, Dr. Brenner and his associates were able to piece together the first complete and reproducible fate map of cell lineage. They later received the 2002 Nobel prize for their work in genetic regulation of organ development and programmed cell death. Being that "c.elegans"are hermaphrodites, there consist of both male and female organs, where they store sperm and are able to self fertilize. "C. elegans"contain 302 neurons and 959 somatic cells, where they begin with 1031, where 72 undergo apoptosis which is programmed cell death. This makes the "c.elegan"a model organism for studying cell lineage, and being able to observe the cell divisions due to their transparent phenotype. One of the first studies of cell lineages took place in the 1870s by Whitman who studied cleavage patterns in leeches and small invertebrates.