ISSN:
1432-1106
Keywords:
Lateral geniculate nucleus
;
Monkeys
;
Golgi type II interneurons
;
Synaptic arrangements
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Total excision of areas 17-18-19 in the monkey leads to disappearance of relay cells and corticogeniculate axon terminals in the LGN (lateral geniculate nucleus). The few remaining neurons can be safely considered as Golgi type II cells. Electron microscopic examination of such material revealed small ovoid neurons and synaptic clusters encapsulated by glia. Within the cluster there were the characteristic axon terminal of retinal origin, and a peculiar light and large profile with features of both axons (small, flattened synaptic vesicles) and dendrites (many microtubules, endoplasmic cisterns and free ribosomes) in varying proportions. These elements were also present within the heavily gliotic general neuropil and, in longitudinal section, showed segments with strongly dendritic features, and others with vesicles either scattered or grouped near synaptic specializations. Similar profiles were also seen in normal LGN. Light microscopic examination of Golgi series from adult normal monkeys revealed two types of interneurons in the LGN, both having extremely thin axons which could not correspond in size to the ambiguous profiles described above. The latter could well match the appendages so frequently shown by the dendrites of one of the interneuron types. These findings suggest that the synapses in the glomeruli of LGN previously defined as “axo-axonic” may in fact be between optic axon terminals and the dendritic profiles with synaptic vesicles delineated in this study. Thence, the role of the Golgi type II interneuron could be interpreted at least in part as lateral inhibition.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00234561
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