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Abstract
The eyes of 10 human fetuses between the eighth week and the eighth month of pregnancy were examined. Meridional sections of the developing cornea were studied with the electron microscope. By the end of the second month mesenchymal cells, at first loosely arranged, have formed a solid strand of corneal endothelial cells. In the following developmental stages these cells get a rich content of endoplasmic reticulum and mitochondria, well developed Golgi complexes, and prominent nucleoli, expressing the activity of the cells. The basement membrane of the corneal endothelium, the membrane of Descemet, increases in thickness by a regular apposition of basement membrane-like lamellae. This lamellar arrangement characterizes the development of Descemet's membrane in the human eye, as opposed to the findings in chickens and rabbits. In many parts of the membrane the typical periodic substructure is visible in the eighth month of gestation. The periodicity is observed in the posterior as well as in the anterior layers, whereas in the adult eye it exists only in the anterior third of the membrane.