In vitro effects of kainate on embryonic and posthatching chick retina.

The onset and developmental pattern of kainate effects were determined in isolated embryonic and posthatching chick neural retinas exposed to KA (0.01-0.24 mM; 1-30 min) in vitro. Damage was first apparent in day 8 embryonic retinas; cells in the inner region of the inner nuclear layer and neuronal processes in the inner plexiform layer were affected. In older embryonic retinas, cells in the inner region of the inner nuclear layer continued to be the most damaged although cells in the ganglion cell layer and the outer region of the inner nuclear layer, and neurites in the outer plexiform layer were also affected. Cells in the outer nuclear layer stained normally in both embryonic and posthatching retinas. Partial reversibility of kainate effects was observed in retinas which had been exposed briefly to kainate and then allowed to recover in kainate-free medium. The results of our in vitro experiments are consistent with those reported for a variety of neonatal and adult retinas treated with kainate in vivo.