Does early enucleation affect the decussation pattern of alpha cells in the ferret?
Naturally occurring cell death has been hypothesized to sculpt various features of the organization of the mature visual pathways, including the recent proposal that the selective elimination of ganglion cells in the temporal retina shapes the formation of decussation patterns. Through a class-specific interocular competition, ganglion cells in the two temporal hemiretinae are selectively lost to produce the decussation patterns characteristic of each individual cell class (Leventhal et al., 1988). The present study has tested this hypothesis by asking whether the removal of one retina in newborn ferrets, which should disrupt binocular interactions at the level of the terminals, alters the decussation pattern of the alpha cells, a cell class that is entirely decussating in the normal adult ferret. Enucleation on the day of birth was found to increase the uncrossed projection by approximately 50%, but not a single uncrossed alpha cell was found in the temporal retina. Either alpha cells never project ipsilaterally during development, or if they do, they cannot be rescued by early enucleation. While naturally occurring cell death plays many roles during development, creating the decussation pattern of the ferret's alpha cell class via a binocular competition at the level of the targets is unlikely to be one of them.
Reese
B E
BE
Neuroscience Research Institute, University of California, Santa Barbara 93106-5060.
Urich
J L
JL
D000818:Animals; D001369:Axons; D002452:Cell Count; D016923:Cell Death; D015353:Eye Enucleation; D005289:Ferrets; D006735:Horseradish Peroxidase; D009897:Optic Chiasm / Q000166:cytology / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology
D006735:Horseradish Peroxidase