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Electrophysiological study revealed a correlation between changes in bioelectric activity of the reticular gigantocellular nucleus and movements of chick embryos during ontogeny (16-20 days). This relationship increased by the end of embryogenesis. The reticular gigantocellular nucleus is the major source of supraspinal influences on motor activity during ontogeny. Blockade of proprioceptive impulses with myorelaxin inhibited bioelectric activity of the regulatory gigantocellular nucleus, which attests to the activating effect of proprioception.

The formation of synapses in ontogenesis is an important problem of neuromorphology. The paper shows that the bulk of synapses of the developing brain is formed on the basis of previous specialization of membranes. Early in ontogenesis, most formed synapses shows asymmetric contacts. In postnatal ontogenesis, the formation of synapses proceeds due to the simultaneous occurrence of specialization of membranes and synaptic vesicles, by forming a "dot" active zone. Systemogenesis, such as the general law of brain development, plays an important role in understanding the functional significance of the shown mechanisms of maturation of synapses.

The paper presented results of a quantitative Golgi study of developing neurons of the brain stem reticular nuclei of prenatal and newborn kittens. Age of prenatal animals was 45-55 days, that of newborns 1-5 and 30 days. The neurons were divided into sparsely ramified reticular and densely ramified multipolar giant ones. The quantitative morphological data were obtained by measuring cellular sizes, number, length and degree of branching of dendrites and general cell branching. The neurons of both kinds had different parameters and special features of their maturation. A higher degree of branching was observed in the fetus. Foci of maximal dendrite branching were localized in proximal and distal portions of dendrites in the fetus and 30-day old kittens, and only in proximal portions in the infant kitten. An attempt was made to correlate morphological and electrophysiological properties of the neurons under study.