Quantitative studies of cytochemical and cytological changes during cell death in the larval fat body of Drosophila melanogaster

Cytometric analysis of larval fat body cells of normal and mutant genotypes was done to ascertain changes in the average cell size, the distribution of cell sizes, and changes in the amounts of cellular reserves after various incubation times in lytic and permissive environments during the lytic phase of cell death. The average cell size becomes smaller in both environments but less rapidly in the permissive environments. The distribution of cell sizes is strikingly broader in the permissive than the lytic environment. Glycogen, lipid, and protein reserves are lost from the cells during the lytic phase but at different rates. Glycogen and lipid reserves are lost independently of the environment. Regardless of whether the environment was lytic or permissive, glycogen disappeared from the cells completely and extremely rapidly whereas lipid disappeared from the cells at a slower rate. Protein was also lost from the cells but the rate was dependent on the environment. There was a rapid loss of protein in the environment which causes rapid cell death, but a gradual loss of protein in the environment where cell death occurs gradually. The relationship of the decrease in cell size and the loss of reserves to the permissiveness of the environment is discussed.