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The fine structure of the perigeniculate nucleus in the cat
Author(s) -
Ide Linda S.
Publication year - 1982
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.902100402
Subject(s) - axon , synaptic vesicle , postsynaptic potential , nucleus , vesicle , biology , geniculate , golgi apparatus , axon terminal , synapse , soma , anatomy , free nerve ending , ultrastructure , biophysics , neuroscience , membrane , biochemistry , cell , receptor
The fine structure of the cat's perigeniculate nucleus has been analyzed and compared to that of dorsal thalamic relay nuclei. Golgi preparations and electron micrographs of perigeniculate cells commonly show somatic spines. The most common presynaptic elements for these spines and for the adjacent perikaryal surfaces are relatively large axon terminals containing round synaptic vesicles and making multiple asymmetric contacts. These “RLD” terminals (so termed for their r ound vesicles, l arge average size of the terminals, and d ark mitochondria) are also presynaptic to dendritic spines and shafts of proximal and secondary dendrites. Comparisons with adjacent parts of the dorsal lateral geniculate nucleus show that these RLD terminals are cytologically distinct from retinogeniculate terminals and that small numbers of RLD terminals also occur in the geniculate A laminae. Three other major classes of perigeniculate synaptic terminals, resemble major classes of terminals in the dorsal lateral geniculate nucleus. These include two types of terminal with f lat or ovoid synaptic vesicles and d ark mitochondria, “FD 1 ” and “FD 2 ” terminals, and a class of small terminal with densely clustered r ound vesicles and d ark mitochondria, “RSD” terminals. RSD terminals, which resemble corticogeniculate axon terminals, represent the only class of perigeniculate terminal that does not contact perikarya. FD 2 terminals resemble lateral geniculate presynaptic dendrites and participate in serial and triadic synaptic contacts, being both pre‐ and postsynaptic; however, in contrast to the arrangement characteristic of thalamic relay nuclei, these contacts do not occur within synaptic glomeruli. A fifth major class of perigeniculate presynaptic terminal has large f lat or polymorphic synaptic vesicles and p ale mitochondria. These “FP” terminals are seen infrequently in the lateral geniculate A laminae. Similarities between perigeniculate and lateral geniculate fine structure may relate in part to common sources of afferent input to the two nuclei.