Morphological feature of Apoptosis:
- Best seen with electron microscope.
- Cell shrinkage:
- Cell becomes small, cytoplasm is dense and organelles are more tightly packed.
- Chromatin condensation:
- Most characteristic feature of apoptosis.
- Nuclear chromatin is condensed, and aggregates peripherally under nuclear membrane into well-defined dense masses of various shapes and sizes.
- Nucleus breaks up producing two or more fragments, reflected as fragmentation of DNA into nucleosome-sized pieces through activation of endonucleases.
- Formation of cytoplasmic blebs (buds) and apoptotic bodies:
- Apoptotic bodies rapidly shrink, then shows extensive surface blebbing and finally undergo fragmentation into a number of membrane bound apoptotic bodies composed of cytosol and tightly packed organelles with or without nuclear fragments.
- Phagocytosis of apoptotic cells or bodies by nearby healthy cells either parenchymal or macrophages.
As apoptotic bodies are quickly thrown out and phagocytosed and degraded within lysosomes they maynot be visible microscopically. Nearby cells migrate or proliferate to replace earlier occupied by apoptotic cell.
