PubMed · 4097321
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J Aminu, A D'Mello, D W Vere. 1970-10-31. Interaction between debrisoquine and phenylephrine.. https://doi.org/10.1016/s0140-6736(70)92115-x
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Optical methods were used to locate the cell bodies of directionally selective ganglion cells in isolated rabbit retinas. These neurons detect the direction in which images move across the retinal surface and transmit that information to the brain. The receptive field of each identified cell was determined, after which the cell was injected with Lucifer yellow. An image of the receptive field border was then projected onto the fluorescent image of the dendrites, allowing precise comparison between them. The size of the receptive field matched closely the size of the dendritic arbor of that cell. This result restricts the types of convergence that can be postulated in modeling the mechanism of retinal directional selectivity.
Single retinal ganglion cells projecting bilaterally to the superior colliculi (SC) by way of axon collaterals were revealed in the Japanese monkey (Macaca fuscata). After injecting Fast blue into the SC on one side and Diamidino yellow into the SC on the opposite side, some retinal ganglion cells were double-labeled with both tracers. Most of them were large cells (more than 25 microns in diameter), and were localized in a narrow strip around the vertical meridian of the retina on each side. This retinal area roughly corresponds to the reported strip of nasotemporal overlap, where both crossed and uncrossed retinofugal projections arise.
This study has examined the deleterious effect of superior colliculus (SC) ablation on the viability of identified retinotectally projecting ganglion cells in the neonatal rat retina. The time-course and extent of lesion-induced retinal ganglion cell (rgc) death has been determined and an estimate obtained for the rate of clearance of individual dying neurons. In order to demonstrate the projection of rgcs to the SC and the subsequent death of these same neurons after SC lesions, the fluorescent dye diamidino yellow (DY) was injected into the left SC of anesthetized 2 day old Wistar rats (P2: day of birth = P0). DY retrogradely labels the nuclei of tectally projecting rgcs; if these identified rgcs subsequently die, their DY-labelled nuclei become pyknotic and can be visualized in retinal wholemounts. At P4 the rats were again anesthetized and the injected area, seen as a yellow patch in the SC, was removed by aspiration. Rats were perfused 2 to 336 hours after the lesion and retinal wholemounts of the right eye were prepared. Control rats received only DY injections and were perfused at times corresponding to the lesioned animals. In three sham-operated rats; the injected SC was reexposed at P4 but the tectal tissue was not removed. In each of the 42 rats that were analyzed, about 10% of the retina containing retrogradely labelled rgcs was counted; the number of pyknotic versus normally labelled rgcs was determined and changes in normal cell density were also assessed. Pyknotic rates in control and sham-operated rats were similar (average 0.8%, n = 11). In SC-lesioned rats, the proportion of pyknotic DY-labelled rgcs increased to about 2.5% 4 to 8 hours postlesion (PL); the peak period of death occurred at 23 hours PL (8.0%). The amount of pyknosis decreased thereafter and most dying cells had been eliminated by 50 hours PL. Phagocytosis of dying cells was a common feature of retinae in SC lesioned rats. In the long-term (336 hours) rats, counts of normal DY-labelled rgcs in corresponding regions of control and lesioned rats revealed an average decrease in rgc density of 47.3% after P4 tectal ablation. Calculations suggest a clearance time of about 3 hours for dying neonatal rgcs.