DIFFERENTIAL ULTRASTRUCTURAL DISTRIBUTION OF SYNAPSIN AND SYNAPTOPHYSIN PROXIMAL TO A LIGATION IN BOVINE SPLENIC NERVE

Synaptophysin and synapsin, closely correlated on synaptic vesicles in terminals, may show a differential distribution at synapse formation and maturation. In order to disclose the fine structural details of th ese differences. synapsin and synaptophysin distribution was studied b y immunocytochemistry on ligated bovine splenic axons in vitro and com pared with terminals in the vas deferens. In the synaptic differentiat ions taking place proximally synapsin could only be detected on the ac cumulating elements of the axonal reticulum. Large dense granules and clusters of small synaptic vesicles were negative. Synaptophysin was r estricted to these clusters. In the vas deferens, co-localization of s ynapsin and synaptophysin could be seen on small vesicles. From their formation small synaptic vesicles carry synaptophysin. Synapsin may be involved in the dynamic membrane changes taking place at the ligation . At a unctional terminal, synapsin shifts to small synaptic vesicles. (C) 1998 Elsevier Science B.V. All rights reserved.