Electron-lucent degenerating geniculate terminals in cat striate cortex.
Degenerating geniculate axon terminals in cat striate cortex have been previously described as electron-dense. After electrolytic lesion of the lateral geniculate nucleus, we observed degenerating terminals in layer 4 of striate cortex which were electron-lucent. The lucent terminals --which co-exist with the dense terminals--are characterized by a pale matrix, large size, distorted mitochondria, and a paucity of synaptic vesicles. They preferentially (82.5%) contact dendritic spines. Lucent terminals were common in layer 4, rare in layer 6, and absent from layers 1 through 3 and layer 5. This distribution is consistent with the projection of the lateral geniculate nucleus to the striate cortex. Thus, geniculate terminals undergo both the electron-lucent and electron-dense degeneration reactions in cat striate cortex, and the lucent terminals make a significant contribution to the amount of degeneration present. The relationship of lucent degeneration to other forms of degeneration is discussed.
Dashe
J F
JF
Department of Anatomy, University of Pennsylvania School of Medicine, Philadelphia 19104.
Davis
T L
TL
D000818:Animals; D002415:Cats; D005829:Geniculate Bodies / Q000166:cytology*; D009410:Nerve Degeneration; D009411:Nerve Endings / Q000502:physiology / Q000648:ultrastructure*; D014793:Visual Cortex / Q000166:cytology*; D014795:Visual Pathways / Q000033:anatomy & histology*