Synophthalmia in an early human fetus

The great majority of reports dealing with human cyclopia and synophthalmia are derived from fetuses at the end of pregnancy. Thus, data concerning early organization of the ocular anlage in this impressive ocular developmental anomaly are almost completely lacking. We therefore present a 12 week-old synophthalmic fetus. After uneventful pregnancy spontaneous abortion occurred. Within the face of the hypotrophic fetus there was a central pigmented ocular anlage with an inferior fissure. A nose (proboscis) was not discernible. Histologically, there were two vesicles caudally which fused to one vesicle cranially. Differentiation was more advanced in the anterior and temporal parts of the anlagen. A coherent inner layer (of the optic cup) was not developed. Trisomy 13 was suspected but could not be proved by FISH-technique. The fetus demonstrates that fusion of the ocular anlagen is finished at the end of the third gestational month and that synophthalmia/cyclopia is very likely to be associated with maldevelopment of the optic cup. As far as we know there is evidence for the first time that organization of the anlagen improves not only in the posterior to anterior and in the medial to lateral but also in the cranial to caudal direction.