Freeze-etched neuronal growth cones from rat cerebral cortex at birth: plasma membrane morphology in relation to synapse formation.

Isolated growth cones from the cerebral cortex of newborn rats were studied using the freeze-etching technique. The intramembranous structure of their plasma membranes was examined in detail and synaptic sites were found. Their membrane morphology was compared with that of the synaptic sites in adult animals and several differences between them were established. The importance of the present results for understanding the formation and development of the synaptic sites in the cerebral cortex is outlined.