The primary optic system in a microphthalmic snake (Calabaria reinhardti)

The retinal projections in the microphthalmic snake Calabaria reinhardti were investigated by means of the radioautographic method following intraocular injections of [3H]proline. The results demonstrated the existence of a general pattern of organization of the primary visual system comparable to that observed in macrophthalmic snakes. However, most of the primary optic centers appeared reduced and showed varying signs of atrophy, whereas others were completely absent. Elsewhere, the ipsilateral visual component appeared as well developed as that found in macrophthalmic snakes. The evolutionary significance of the differential microphthalmic pattern of organization of the primary visual system is discussed.