Cell lineage

Cell lineage denotes the developmental history of a tissue or organ from the fertilised embryo.^[1] Cell lineage can be studied by marking a cell 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.^[2][3] This causes the cell lineage and cell fate to be highly correlated.

Studies of cell lineage

One of the first studies of cell lineages took place in the 1870s by Whitman who studied cleavage patterns in leeches and small inverterbates.^[4] He found that some groups, such as nematode worms and ascidians form a pattern of cell division which is identical between individuals and invariable. This high correlation between cell lineage and cell fate was thought to be determined by segregating factors within the dividing cells. Other organisms had stereotyped patterns of cell division and produced sublineages which were the progeny of particular precursor cells. These more variable cell fates are thought to be due to the cells' interaction with the environment.^[5]

Cell lineage can be determined by two methods, either through direct observation or through clonal analysis. During the early 19th century direct observation was used however it was highly limiting as only small transparent samples could be studied. With the invention of the confocal microscope this allowed larger more complicated organisms to be studied.^[6]

References