Unilateral anophthalmia in a Holstein calf.

Unilateral anophthalmia in a Holstein calf was examined morphologically. On the left side, a small cystic remnant of the eye ball (CRE) was present in the orbit. The CRE was adhered to the dura mater through an abnormal foramen formed in the orbital region of the cranial base. At this region of the left cerebral hemisphere, a porencephalic change was detected. Histologically, the pigment epithelium was continued from the lining of the inner surface of CRE to the residual cerebrocortical tissue attached to the dura mater. These characteristic changes seem to suggest the partial fusion of the outer layer of the optic cup to the telencephalon during optic organogenesis.