Cerebellar glia cells induce a correct laminar organization in chicken retinal reaggregates

We investigated the functional role of glia cells during retinogenesis usin g the rotation culture system. Reaggregating cells from the embryonic chick retina have the unique capacity to reassemble into laminated cellular sphe res. These spheres are composed of several compartments holding the constit uents of many retinal layers in a topologically correct, yet inverse orient ation. However, when these spheres are cultured in the presence of conditio ned media derived from monolayers of cerebellar glia cells, the reassemblin g retinal cells behave totally differently. The anlage of the originally re versed lamina polarity is progressively transformed within a week into a sp here with a compound and correctly laminated orientation. Conditioned media from fibroblasts, other glia cells (except Muller cells) or a set of alrea dy characterized retinogenetic factors are not able to produce this dramati c transformation. Additionally, we were able to show that only retinal cell s are able to respond with a reorganization process. Reaggregating cells fr om the chick cerebellum also form spheroids; however, neither in the presen ce of cerebellar glia cellderived conditioned medium nor their control coun terparts are they able to reassemble histotypically. This indicates that ce rebellar glia cells produce diffusible factors to which retinal cells can r espond and that these factors can act as important determinants for the cor rect establishment of the retinal polarity. Since all types of laminar diso rganization are of great clinical significance, the knowledge of factors wh ich determine and sustain the normal retinal architecture are biomedically highly relevant. Copyright (C) 2001S.KargerAG,Basel.