SYNAPTIC ORGANIZATION OF AN ORGANOTYPIC SLICE CULTURE OF THE MAMMALIAN RETINA

Vertical slices of postnatal day 6 (P6) rat retina were cut and cultur ed using the roller-tube technique. The organotypic differentiation du ring a culture period of up to 30 days has been described in a previou s study (Feigenspan et al., 1993a). Here we concentrated on the synapt ic organization in the retinal slice culture. Electron microscopy reve aled the presence of ribbon synapses in the outer plexiform layer and conventional and ribbon synapses in the inner plexiform layer. Immunof luorescence with antibodies that recognize specific subunits of GABA(A ) or glycine receptors revealed a punctate distribution of the recepto rs. They were aggregated in ''hot spots'' that correspond to a concent ration of receptors at postsynaptic sites. Different isoforms of GABA( A) and glycine receptors occurred in the slice cultures. The experimen ts show that there is a differentiation of synapses and a diversity of transmitter receptors in the slice cultures that is comparable to the in vivo retina.