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Volume 4 No. 2, April 2009 |
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Projection Patterns of Uncrossed Retinal Ganglion Cells in the Golden Hamster Hanie Abdel-Hamid Youssef, Ph.D. Department of Anatomy, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
(Formerly, research fellow at Kobe University School of Medicine,
Japan)
Aim: The aim of this study was to investigate the projection
patterns of the retinal ganglion cells that project ipsilaterally to
primary visual targets in the golden hamster. Methods: The
retrograde fluorescent tracers, Fluoro-Gold (FG) and
4',6-diamidino-2-phenylindole dihydrochloride (DAPI), were injected
into the lateral geniculate body (LGB) and the ipsilateral superior
colliculus (SC) of golden hamsters (Mesocricetus auratus).
Examination of the ipsilateral retina revealed that some retinal
ganglion cells (RGCs) were labeled as follows: (1) double-labeled
cells, indicating double projection to LGB and SC; (2)
single-labeled LGB-projecting RGCs; and (3) single-labeled
SC-projecting RGCs. The cell soma size was measured, and the
soma-size distribution was compared among the three classes in the
ipsilateral retina as well as with the corresponding class in the
contralateral retina. Results: The ipsilaterally projecting
double-labeled RGCs had significantly larger mean soma size than the
other two classes. In the contralateral retina, the SC-projecting
RGCs had significantly smaller mean soma size than the other two
classes. When both retinas were compared, only the ipsilaterally-projecting
double-labeled RGCs had a significantly larger soma size.
Conclusion: The double-projecting RGCs have axon collaterals that
probably provide afferent input to the central targets concerned
with light and visual stimulation.
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