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Some observations on the early development of the optic tectum in the frog ( Rana pipiens ), with special reference to the effects of early eye removal on mitotic activity in the larval tectum
Author(s) -
Currie Julia,
Cowan W. M.
Publication year - 1974
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.901560202
Subject(s) - biology , tectum , rana , anatomy , ependymal cell , mitosis , neuroscience , cerebrum , optic tectum , retina , optic nerve , ganglion , phoxinus , microbiology and biotechnology , midbrain , central nervous system , cyprinidae , fishery , fish <actinopterygii>
Following unilateral eye removal in Rana pipiens at embryonic stages 21–24 there is a statistically significant reduction in the numbers of mitoses found in the contralateral optic tectum at larval stage XIV amounting to approximately 16 per cent. Most of the reduction in mitotic activity occurs in the rostral third of the tectum and does not appear to involve its caudal pole, where cell proliferation is most vigorous. Since thymidine autoradiography indicates that the majority (if not all) of the cells being generated in the rostral third of the tectum at stage XIV are either glial or ependymal cells, it is suggested that the primary effect of eye removal on cell proliferation in the tectum is upon gliogenesis. Using the autoradiographic method for tracing axonal connections, it has been found that the axons of the retinal ganglion cells reach the tectum by embryonic stage 22, and by larval stage XIV have spread to all but its caudomedial region.