Fiber-fiber interaction and tectal cues influence the development of the chicken retinotectal projection.

The development of the retinotectal projection has been studied by a new experimental approach combining antibodies against the nerve cell adhesion molecule (NCAM), and techniques for mapping neuronal pathways using rhodamine B isothiocyanate (RITC) crystals. Anti-NCAM Fab', which specifically inhibits neurite fasciculation, was injected into the eye cup of 4-day-old chicken embryos. After 4-6 days of development, a small RITC crystal was placed on the neural retina to stain selectively axons arising from a localized region.

Elimination of ipsilateral retinotectal projections in mono-ophthalmic chick embryos.

There are two transient ipsilateral retinotectal projections in the chick embryo: a normal one, appearing with a similar projection pattern in both binocular and monocular embryos, and an additional abnormal projection appearing only in mono-ophthalmic embryos. The development and the elimination of the ipsilateral retinotectal projections in mono-ophthalmic chick embryos was investigated using horseradish peroxidase (HRP) and the fluorescent dye Rhodamine-B-Isothiocyanate (RITC) as tracers for axonal pathways. The mechanisms involved in the elimination of the ipsilateral fibers are discussed.

Investigations on the development and topographic order of retinotectal axons: anterograde and retrograde staining of axons and perikarya with rhodamine in vivo.

Rhodamine-B-isothiocyanate (RITC) is shown to be a convenient and advantageous fluorescence tracer both for anterograde staining of retinal ganglion cell axons on the tectum and for retrograde staining of ganglion cell bodies in the retina of chick embryos. After intravitreal injection the dye is taken up by ganglion cells of the retina from the extracellular space and is transported anterogradely at about 10 mm/day up to the axonal growth cones on the tectum. RITC can be taken up by growing axons on the tectum and it is transported retrogradely at about 5 mm/day to the cell bodies in the retina.