[Ultrastruct characteristics of neurons and synapses in the central cortex during circulatory hypoxia].

During short-term (3.7 and 15 min) circulatory hypoxia (ischemia) pronounced ultrastructural changes, having an obvious focal character, were observed in the rabbit cerebral cortex. In some regions, the extracellular space was widened; in the neurons, changes are seen both in the nucleus (appearance of polymorphic vacuoles and deep invaginations of nuclear envelope, aggregation of chromatin) and cytoplasmic organelles (mitochondrial swelling, swelling of profiles of endoplasmic reticulum, dislocation of ribosomes). Most striking reactions were observable in synapses - the number of synaptic vesicles was sharply reduced, its location in the axon terminal changed, the dense material associated with pre- and postsynaptic membranes was enlarged, mitochondria were swollen. The degree of the above alterations was proportional to the duration of ischemia.