The Jaina Doctrine of Karma And The Science Of Genetics: Control Of Cell Growth And Reproduction

We know very little about the mechanisms that maintain proper numbers of the different types of cells in the body. However, experiments have shown at least three ways in which growth can be controlled:

1. Growth is often controlled by growth factors that come from other parts of the body. Some of these circulate in the blood, but others originate in adjacent tissues. For instance, the epithelial cells of some glands, such as pancreas, will fail to grow without a growth factor from the sublying connective tissue of the gland.
   
   
2. Most normal cells will stop growing when they have run out of space for growth. This occurs when cells are grown in tissue culture, the cells grow until they contact a solid object and then growth stops.
   
   
3. Cells grow in tissue culture often stop growing when minute amount of their own secretions are allowed to collect in the culture medium. This, too, could provide a means for negative feed back control of growth.^[34]