The normal colonic crypt demonstrates gradients of expression of members of the Bcl-2 family, suggesting that these proteins are involved in the control of apoptosis in the colonic epithelium. In the colon, the luminal composition, systemic factors, endogenous cytokines and local effects such as basement membrane components may all contribute to the susceptibility of a cell to undergo apoptosis. The culture of adenoma cells, a premalignant stage in colorectal carcinogenesis which maintains many of the characteristics of normal cells, enables investigations of the importance of these factors and the mechanisms by which they regulate tissue homeostasis. Apoptosis was originally defined according to morphological criteria. These dyes are mutagens and therefore should be handled wearing gloves.
Special disposal is required.
Early apoptotic cells have dense chromatin which lines the nuclear membrane in crescent shapes. This is accompanied by cell shrinkage. The cell may fragment into smaller apoptotic bodies. In contrast, necrosis, or accidental cell death is characterised by flocculation of chromatin, which appears as an empty looking nucleus. Loss of substrate adherence is an early event in apoptosis of colonic adenoma cells Epithelial cell cultures such as colorectal adenomas present difficulties to the apoptosis investigator by virtue of their requirement for substrate adherence.