1995 Volume 14 Issue 1-2 Pages 1-2_39-1-2_47
The retina of suckling beagles up to 6 weeks of age was observed morphologically and the relationship between functional and morphological developments in the posterior portion of eye was discussed. As early as 1 week after the birth, the nerve fiber, ganglion cell, inner plexiform and outer neuroblastic layers were histologically identified. The rods and cones layer was found near the external limiting membrane. Tapetal cells exhibited spindle-shaped contour and irregularly arranged. Electron microscopically, synapses were hardly found in the inner plexiform layer at 1 week of age. At 2 weeks of age, the neuroblastic layer which had been identified between the inner plexiform layer and the external limiting membrane at 1 week of age differentiated into 3 layers to form the inner granular, outer plexiform and outer granular layers. At this time point, numerous synapses with abundant synaptic vesicles were seen in the neurons of inner plexiform layer. At 3 weeks of age, the inner and outer segments were distinguished in the rods and cones layer. The axons of photoreceptor cells extended into the outer plexiform layer. At 6 weeks of age, the overall structure of the retina was almost same with that of the adult, and tapetal cells have developed well and regularly arranged like as pavement. Above mentioned morphological sequence of retinal differentiation, concentrated during 3 weeks from 2 weeks of age, was closely related to the functional development as revealed electrophysiological examination.
