The capacities of retinal and pigmented cells to regenerate histotypic in-vitro-retinae (IVR) in rotary culture were investigated by dividing the eye cups of 6-day-old chicken embryos into a central and a peripheral part; they were cut along the ora serrata, and the retinal and the pigmented constituents of both parts were isolated. The 4 dissociated cell populations were cultured separately and in all double combinations. Two different types of IVR's were generated; one developed from central or peripheral retinal cells, the other required the addition of pigmented cells from the ciliary margin of the eye. The shape of these IVR's was examined using scanning electron microscopy, and they were also characterized histologically. The acetylcholinesterase pattern marked the inner half of the retina; F11-antibody and a peanut agglutinin marker revealed both plexiform layers and a radial fiber system. In both types, organized histotypical areas consisted of complete sets of retinal layers. In the type containing pigmented cells from the eye periphery, the sequence of layers was identical with that of an in-situ-retina ("laminar IVR"). In IVR's derived from retinal cells only, the sequence of layers was reversed ("rosetted IVR").