Cell distributions in the retinal ganglion cell layer of adult Leptodactylid frogs after premetamorphic eye rotation.

In adult Limnodynastes dorsalis and Heleioporus eyrei regions of high cell density in the retinal ganglion cell layer are normally found along the nasotemporal axis and become apparent only after metamorphosis (Dunlop & Beazley, 1981; Coleman, Dunlop & Beazley, 1984). Eye rotations were performed from embryonic to mid-larval life and cell topography mapped after metamorphosis using cresyl violet-stained wholemounts. Mature cell distributions indicated that from stages equivalent to 30/31 in Xenopus (Nieuwkoop & Faber, 1956) alignment of high cell density regions had already been determined and developed to reflect the degree of eye rotation. We conclude that cell topography in the adult ganglion cell layer is determined from the time at which invagination of the eye cup nears completion. Furthermore, the correspondence in adults between alignment of high cell density regions and the orientation of the visuotectal projection suggests that these features could not be dissociated by manipulation of the developing eye.