Electron microscopy of the early embryonic development of the human corneal epithelium.

The eyes of a human embryo in the 6th week, 11 mm crown-rump (C.R.) length, and of a human embryo in the 7th week, 19 mm C.R. length, were examined. In the embryo of 11 mm C.R. length, the lens vesicle had just detached from the surface ectoderm, the presumptive corneal epithelium. The acellular primary corneal stroma appeared between the lens vesicle and the overlying ectoderm. The fine structure of the ectodermal cells, of their basal lamina, and of the primary stroma is described. In the embryo of 19 mm C.R. length, mesenchymal cells had moved from the periphery into the space between the ectoderm and the lens. There were remarkable changes in the structure of the corneal epithelial cells, in their basal lamina, and in the underlying substances of the primary stroma.