STRUCTURAL AND ULTRASTRUCTURAL-CHANGES IN THE DEVELOPMENTAL PROCESS OF PREMATURE-INFANTS AND CHILDRENS CORNEAS

Seven corneas ranging in age from 20 weeks of gestation to 6 months af ter birth were studied and changes observed in five layers. The epithe lium thickens through the addition of new cellular layers and the enla rgment of cells. The way junctional complexes develop with age is desc ribed. The way the collagen fibrils in Bowman's layer is arranged chan ges over time. The layer arrangement and orientation of the stroma's c ollagen fibrils are described at different stages of development. The keratocytes progressively flatten out and gather together. The thickne ss of Descemet's membrane increases from 0.6 m at 20 weeks of gestatio n to 4 m at 6 months. During the prenatal period, the banded layer app ears with cross-linking bridges. The nonbanded layer appears after bir th. Several changes were found in the endothelium: flattening out of t he initially cube-shaped cells and changes in the intercellular juncti ons that can be seen from 20 weeks of fetal life. At 20 and 25 weeks o f gestation, two layers of cells were observed in the corneal midperip hery. The adult structure of the cornea was reached at about 6 months after birth.