Retinogeniculate projections in the rabbit: an autoradiographic study.

As shown by autoradiographic techniques, the pattern of retinogeniculate projections in the pigmented rabbit is generally similar to that described in previous studies. Each retina projects bilaterally to the alpha segment of the dorsal lateral geniculate nucleus (LGd) and to the external segment of the ventral lateral geniculate nucleus (LGv). The beta segment of the LGd and internal layer of the LGv receive contralateral inputs only. The alpha segment of the LGd contains an irregularly shaped region which receives overlapping bilateral projections. Within this region the ipsilateral input is continuous and predominant. This pattern of ipsilateral projection can account for both the laminar arrangement perpendicular to the lines of projection and the "hidden lamination" which have been described previously for the rabbit LGd. A separate bilateral projection is identified for a group of cells lying between the LGd and LGv rostrally. Caudally this intergeniculate leaflet extends medial and ventral to the LGv and appears to merge with the zona incerta.