ULTRASTRUCTURAL AND BIOCHEMICAL COMPARISONS OF DENDRODENDRITIC SYNAPTOSOMES FROM BOVINE SUPERIOR COLLICULI AND OLFACTORY BULBS WITH AXODENDRITIC AND AXOSOMATIC SYNAPTOSOMES

Abstract– The buoyant density, ultrastructure and protein composition of dendrodendritic (DD), axodendritic (AD) and axosomatic (AS) synaptosomes were compared. DD synaptosomes prepared from either bovine superior colliculi or olfactory bulbs sedimented in 0.32 m‐sucrose at 1000 g whereas AD and AS synaptosomes from frontal and temporal lobe cortices sedimented at 10.000 g. In gradients of Renografin the DD contacts banded at a density of 1.12 whereas AD and AS banded at 1.07. The DD contacts appeared as large clusters of serial contacts, and each individual terminal had a mean surface area of 1.48 μm2; the mean area of AD and AS terminals was less than 0.35 μm2. The protein compositions of DD, AD and AS synaptosomes were quite similar, with minor exceptions. These findings suggest that different synaptosmal types evolved from common membrane constituents. Copyright © 1979, Wiley Blackwell. All rights reserved