The geniculohypothalamic pathway in a congenitally anophthalmic mouse.

In a previous study we described abnormalities in cytoarchitecture and vasoactive intestinal polypeptide distribution in the suprachiasmatic nucleus (SCN) of anophthalmic mice. However, the effect of anophthalmia on the geniculohypothalamic pathway, an important pathway for relay of photic information to the SCN, is not known. The present study examined the geniculohypothalamic pathway in congenitally anophthalmic and sighted control mice. The data demonstrate that the development of an intergeniculate leaflet (IGL), the expression of neuropeptide Y (NPY) by IGL neurons and the formation of NPY terminal fields in the SCN proceed in the absence of retinal input. Although the cytoarchitectural organization of the anophthalmic IGL differs from that of the control mouse, the distribution of NPY plexuses in the suprachiasmatic nucleus is remarkably similar.