CYTOCHEMISTRY OF SYNAPTOSOMES

The effects of neuraminidase and testicular hyaluronidase on the ultrastructure of synaptosomes, prepared from hippocampi of female Sprague-Dawley rats, were evaluated in sections of glutaraldehyde-fixed specimens by electron microscopy. Whereas incubation in testicular hyaluronidase (80 μl/ml) was without apparent effect, neuraminidase (100 U/ml) caused a decrease in the visualized densities of presynaptic and postsynaptic processes and, especially, the intervening synaptic cleft. The decrement in density of the synaptic cleft, also demonstrated microdensitometrically, suggested that at least some of the sialic acid freed from synaptosomes by incubation in neuraminidase is located extracellularly, within the synaptic cleft. © 1969.