Physiological cell death of chondrocytes in vivo is not confined to apoptosis: NEW OBSERVATIONS ON THE MAMMALIAN GROWTH PLATE

摘要: Chondrocytes at the lower zone of growth plate must be eliminated to facilitate longitudinal growth; this is generally assumed involve apoptosis. We attempted provide definitive electron-microscopic evidence apoptosis in chondrocytes physes and chondroepiphyses rabbit. were, however, unable find a single chondrocyte with ultrastructure 'classical' vivo, although such cell was found vitro. Instead, condensed had convoluted nucleus patchy chromatin condensations while cytoplasm dark excessive amounts endoplasmic reticulum. These cells were termed 'dark chondrocytes'. A detailed study their combined localisation methods situ suggested different mechanism programmed death. In addition, another type death identified among immature chondroepiphysis. same as chondrocytes, but lumen reticulum expanded fill entire non-nuclear space, all organelles been reduced dark, worm-like inclusions. Since these appeared 'in limbo', they 'paralysed' cells. It proposed that chondrocytes' 'paralysed cells' are examples physiological which does not possible confinement within lacunae, would prevent phagocytosis apoptotic bodies, necessitates mechanisms elimination.