The morphology of microtubules in incubated synaptosomes. Effect of low temperature and vinblastine.

A time-dependent rise in the percentage of microtubule-containing synaptosomes was observed reaching a 41--47% peak after 30 min incubation at room temperature (22--25 degrees C) in a saline medium. Fixation at low temperature or incubation with vinblastine decreased markedly the number of synpatosomes containing microtubules. It was concluded that incubation with cations and processing at room temperature were prerequisites of optimal preservation of synaptosomal microtubules. Their spatial orientation relative to the synaptic cleft was deduced from statistical examination of profiles in different orientations.