[Structural aspects of the development and formation of growth cones in the sensorimotor cortex and caudate nucleus in ontogeny].

The structural organization and formation of the growth cones were studied on the basis of differentiating neurons and processes of the sensorimotor cortex and the caudate nucleus of rats in ontogenesis. Vesicles have been shown to be the major structural unit of the pericarial growth cones and the growth cones of the processes in the cerebral formations studied. The growth cones of the caudate nucleus show more frequently both vesicles and some cytoplasmic organelles as compared with those of the sensorimotor cortex. The growth cones are maximally pronounced at the end of the first postnatal week when the intensive growth and development of the dendrite tree and the ramification of axon terminals are observed. Simultaneously with the formation of the growth cones, their degeneration occurs as well; the latter being noted in animals of all the age groups studied. The questions concerning the formation of the growth cones and the genesis of the vesicular components of these formations are discussed.