The relevance of apoptosis for cellular homeostasis and tumorigenesis: MORPHOLOGY AND DETECTION Part 1

Morphological features of apoptosis: The seminal work of Kerr et al in 1972, building on earlier observations in vertebrates and insects, should be read by those interested in assaying apoptosis because of the excellent photomicrographs that document the morphological features of the process. Fast and reliable shopping for drugs – cialis professional 20 mg to get safe shopping atmosphere.

The morphological features of apoptosis can be separated, for clarity, into three sequential phases. Initially, a cell loses contact with its neighbours and detaches from its substratum; the chromatin becomes condensed into crescent-like caps at the nuclear periphery. There is nucleolar disintegration, compaction of organelles with endoplasmic reticulum dilation, clumping of ribosomal particles, cyto-skeletal filament aggregation and cytoplasmic volume reduction. There is also loss of specialized surface structures such as microvilli and junctional structures. In the second phase, blebs of plasma membrane develop, which can split away from the cells. This is a very dramatic process and can give the cells a ‘boiling’ appearance when viewed on time-lapse video microscopy. Both the nucleus and the cytoplasm split into fragments of various sizes, with the remaining cell becoming a round, smooth membrane-bound body referred to as an ‘apoptotic body’. In the third phase, there is progressive degeneration of the residual nuclear material and cytoplasmic structures. At this stage, the plasma membrane becomes permeable to dyes such as tryptan blue. Apoptosis is rapid and is often completed in vivo in 4 to 8 h, but it may be much quicker in embryogenic cell systems and in some cell cultures.

Category: Gastroenterology

Tags: Apoptosis, bcl-2 family, Gastrointestinal cancer, Intestinal crypt, p53, Stem cell