[Characteristics of the neuronal composition of the central nervous system of nudibranch mollusks].

Studies have been made on the neuronal composition of the central nervous system of the Nudibranch molluscs from the White Sea -- Coryphella rufibranchialis, Dendronotus arborescens and Cadlina laevis -- at various stages of their postlarval development, Localization maps for the largest neurons were composed. For C. rufibranchialis and D. arborescens, about 65--78 neurons were mapped; some of the characteristics of these neurons were investigated, such as age changes in the body size, the shape, pigmentation and neurosecretory activity. Using impregnation of silver nitrate into slices, two types of branching of neuronal processes were revealed (nervous cells with "branching" and "bifurcational" axons).