Geniculotectal neurons of the lateral part of the ventral lateral geniculate nucleus in the hereditary microphthalmic rat: a retrograde WGA-HRP study.

The distribution and morphological characteristics of the geniculotectal neurons from the lateral part of the ventral lateral geniculate nucleus in the hereditary microphthalmic rat were examined by the WGA-HRP method. Unilateral injection of the tracer into the microphthalmic superior colliculus showed that WGA-HRP-positive neurons were present in the ipsilateral lateral part of the ventral lateral geniculate nucleus. However, the number of labeled geniculotectal neurons of the microphthalmia was about 50% that of the normal rats. Furthermore, the size of labeled geniculotectal neurons of the microphthalmia was smaller and their dendrites were shorter than those of normal rats. These results demonstrated that, although geniculotectal neurons of the microphthalmic lateral part of the ventral lateral geniculate nucleus could differentiate just as in the normal rat, the size and number of microphthalmic geniculotectal neurons were remarkably smaller and fewer than those of normal rats. Moreover, the dendrites of microphthalmic geniculotectal neurons were less branched than usual.