[Dark and light neurons in the cortical plate of the forebrain of the swamp turtle].

Electron microscopic study of the neuronal composition of Emys orbicularis cortical zones as compared with the light microscopy data has revealed that the distinctions in the cell cytoplasm ultrastructure with respect to the dendrite branching pattern and the peculiarities of their localization in the cortical plate are suggestive of a possible metabolic heterogeneity and can serve as a foundation of the morpho-functional characteristics of the neurons. A few neuronal types of neurons have been revealed: 1. light neurons distinguished by the cytoplasm matrix devoid of any electron density, a poorly developed endoplasmic reticulum and a few cytoplasmatic organells and inclusions; 2. light neurons having slight osmophility of the cytoplasm matrix, a more developed endoplasmic reticulum with elongated cisternae, a great number of organells including neurofilaments; 3. dark neurons having a high degree of cytoplasm matrix and the nucleus, a large number of the nuclei, cytoplasm, dendrites and axons in contrast to the above described patterns.