Morphological characteristics of apoptosis and its significance in neurogenesis.

Results from our own studies and published data are used to provide a critical analysis of current views of the role of apoptosis in regulating the quantitative and qualitative constancy of cells in the developing brain. Detailed descriptions of the morphological features and mechanisms of the different phases of apoptotic neuron death are given. Apoptosis affects the ordering of connections in neural networks and is involved in the pathogenesis of neurodegenerative diseases--epilepsy, schizophrenia, and Alzheimer's disease. The question of the interaction of the NO-ergic mechanism and the cell in executing apoptosis is discussed. The data allow NO to be regarded as a cytotoxic factor which induces apoptosis. The ultrastructural features of post-mitotic immature neurons suggests the operation of the apoptotic and necrosis-like (NO-dependent) pathways of natural cell death during the process of differentiation.