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Primary optic pathways in the echidna, Tachyglossus aculeatus : An experimental degeneration study
Author(s) -
Campbell C. B. G.,
Hayhow W. R.
Publication year - 1971
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.901430108
Subject(s) - pretectal area , optic tract , nucleus , biology , superior colliculus , anatomy , neuroscience , inferior colliculus , diencephalon , optic nerve , central nervous system , midbrain
The retinofugal axons of Tachyglossus aculeatus were found to project to two diencephalic nuclei, disparate in size and location and designated provisionally as LGNa and b, and to the pretectum and superior colliculus. The primary optic pathways of the echidna are crossed except for a few fibers which pass to the ipsilateral large diencephalic nucleus (LGNa). Further work is required before the homologies of the two diencephalic nuclei can be determined. In addition, entirely crossed projections were also found to a large number of optic nuclei including a medial terminal nucleus, four cell groups interstitial to the optic tract, and a nucleus located within the brachium of the superior colliculus which may represent a dorsal terminal nucleus. The latter nucleus may, however, actually be the nucleus of the optic tract which is displaced from its usual close association with the pretectal area. Only an inferior fasciculus of the accessory optic tract was found.