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 st udied using the freeze-etching technique. The intramembranous structur e of their plasma membranes was examined in detail and synaptic sites were found. Their membrane morphology was compared with that of the sy naptic sites in adult animals and several differences between them wer e established. The importance of the present results for understanding the formation and development of the synaptic sites in the cerebral c ortex is outlined.