PERICAPILLARY AND DISTANT AXON TERMINALS IN THE NUCLEI OF THE CAT AMYGDALA - A MORPHOMETRIC STUDY

According to some ultrastructural studies, the pericapillary axon term inals in the central nervous system (CNS) are functionally connected w ith the capillary vessel wall. Thus, it may be expected that the popul ation of pericapillary axon terminals will be morphologically distinct from the terminals at a further distance from the capillary walls. To test this hypothesis, morphometrical analysis of 3,048 axon terminals was performed, comparing terminals situated in the close vicinity of the capillary vessel with those at a distance from the vessels in the lateral, basal, medial, central and corti cal nuclei of the amygdaloid body of eight cats. The cross-sectional area and circumference of eac h identified axon terminal profile were measured, and the shape of syn aptic vesicles and the presence of synaptic contacts and granular vesi cles were recorded. The statistical evaluation of results was performe d by means of the Newman-Keuls' test, Wilcoxon's test, Fisher's contin gency-table test and the test for two coefficients of structure. The m orphometric examination revealed two ultrastructurally distinct groups of axon terminals, pericapillary and distant terminals, in all the nu clei of the amygdaloid body. The differentiating features were the sha pe of the synaptic vesicles, the number of synaptic contacts, and the size of the axon terminals. These results further support the hypothes is of a functional connection between axon terminals and the capillary vessel wall in the CNS.