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Structural and ultrastructural changes in the developmental process of premature infants' and children's corneas
L Lesueur1, J L Arne, M Mignon-Conte
1Service d'Ophtalmologie, Hopital Purpan, Toulouse, France.
Insights
This study details the developmental changes in the five layers of the cornea from fetal development to 6 months post-birth. Key findings include structural maturation of the epithelium, stroma, Descemet
Area of Science:
- Ophthalmology
- Developmental Biology
- Histology
Background:
- The cornea's layered structure is crucial for vision.
- Understanding corneal development is essential for addressing congenital vision defects.
Purpose of the Study:
- To investigate the developmental changes in the five layers of the human cornea.
- To describe the morphological maturation from 20 weeks gestation to 6 months post-birth.
Main Methods:
- Histological examination of seven corneas across a developmental timeline.
- Microscopic analysis of cellular and extracellular matrix changes.
Main Results:
- Epithelial thickening and cell enlargement observed.
- Collagen fibril arrangement in Bowman's layer and stroma evolves.
- Descemet's membrane thickness increases significantly; banded and non-banded layers form.
- Endothelial cells flatten, and junctional complexes mature.
- Adult corneal structure achieved by 6 months post-birth.
Conclusions:
- The cornea undergoes significant structural development and cellular reorganization post-conception.
- Specific developmental timelines exist for each corneal layer, culminating in adult structure by 6 months.
- These findings provide a detailed map of normal corneal development.
Abstract:
Seven corneas ranging in age from 20 weeks of gestation to 6 months after birth were studied and changes observed in five layers. The epithelium thickens through the addition of new cellular layers and the enlargement of cells. The way junctional complexes develop with age is described. The way the collagen fibrils in Bowman's layer is arranged changes over time. The layer arrangement and orientation of the stroma's collagen fibrils are described at different stages of development. The keratocytes progressively flatten out and gather together. The thickness of Descemet's membrane increases from 0.6 m at 20 weeks of gestation to 4 m at 6 months. During the prenatal period, the banded layer appears with cross-linking bridges. The nonbanded layer appears after birth. Several changes were found in the endothelium: flattening out of the initially cube-shaped cells and changes in the intercellular junctions that can be seen from 20 weeks of fetal life. At 20 and 25 weeks of gestation, two layers of cells were observed in the corneal midperiphery. The adult structure of the cornea was reached at about 6 months after birth.