Abnormal retinogeniculate projections in the congenitally microphthalmic cat.

The retinogeniculate projections from the normal eye of a unilaterally microphthalmic cat are abnormal in that optic tract fibers cross laminar borders and end, inappropriately, in geniculate layers that would normally receive input from the microphthalmic eye. This congenitally induced abnormal retinogeniculate projection is quite similar to that seen in cats with one eye surgically removed shortly after birth. Although most cells are shrunken in the laminae normally innervated by the microphathalmic eye, cells in the region of the abnormal projection appear normal. The normal pattern of geniculate lamination is also disrupted in that cell-free interlaminar regions are considerably more difficult to define in the microphthalmic cat.