[Ultrastructure of rat cerebral cortex neurons at different levels of motor activity].

The reaction of neurons in rat motor cortex during the intensive motor activity and fatigue caused by swimming was investigated with the electron microscope. In both the cases the nuclear envelope in the neuron perikaryon was sharply enlarged resulting in the appearance of deep invaginations; the nucleolus displaced towards the nuclear envelope. Components of the endoplasmic reticulum and Golgi complex increase in size and number, ribosomes become more numerous, the cytoplasm getting denser. During fatigue the above changes appear more pronounced in addition to mitochondrial swelling, the matrix becomes less dense and cristae less numerous. These changes suggest the intensification of metabolitic activity of the cortical neurons during both the intensive motor activity and fatigue.