Why does a skin cell divide more often than a liver cell?
1 Answer
Skin is covered by epithelial cells. Liver is mainly made up of hepatocytes though fibrous and fatty tissues are also present.
Explanation:
Cells of skin epithelium are present in different layers. Lower most layer on basement membrane (all epithelia possess this barrier on which epithelial cells grow) are newly generated. These cells gradually acquire a protective protein keratin but loses vitality. Thus by the time cells reach top most layer of skin they are all dead cells.
Skin loses dry and dead cells from top layer everyday. These cells are replaced by continuous cell division taking place at basal layer of skin epithelium. It takes a new cell about a month to reach the top most layer and being finally shed off. Thus a faster form of cell cycle regulation operates in skin epithelium.
In an adult liver regular cell replacement is not needed (as physical growth has stopped), and cell cycle is generally in G0 stage. This phase allows cells to become adapted for highly specific activities. Hepatocytes may divide in adult life when there is removal of part of liver.
