Akhtar S, Schonthaler HB, Bron AJ, Dahm R. Formation of stromal collagen fibrils and proteoglycans in the developing zebrafish cornea.
Acta Ophthalmol 2008;
86:655-65. [PMID:
18221494 DOI:
10.1111/j.1600-0420.2007.01135.x]
[Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE
Collagen fibrils and proteoglycans are the main components of the corneal extracellular matrix and corneal transparency depends crucially on their proper arrangement. In the present study, we investigated the formation of collagen fibrils and proteoglycans in the developing cornea of the zebrafish, a model organism used to study vertebrate embryonic development and genetic disease.
METHODS
We employed thin-section electron microscopy to investigate the ultrastructure of the zebrafish cornea at different developmental stages.
RESULTS
The layering of the zebrafish cornea into an epithelium, a Bowman's layer, stroma and endothelium was observed starting at 72 hr post-fertilization. At this stage, the stroma contained orthogonally arranged collagen fibrils and small proteoglycans. The density of proteoglycans increased gradually throughout subsequent development of the cornea. In the stroma of 2-week-old larvae, the collagen fibrils were organized into thin lamellae and were separated by very large, randomly distributed proteoglycans. At 4 weeks, a regular arrangement of proteoglycans in relation to the collagen fibrils was observed for the first time and the lamellae were also thickened.
CONCLUSION
The present study, for the first time, provides ultrastructural details of collagen fibril and proteoglycan development in the zebrafish cornea. Furthermore, it directly correlates the collagen fibril and proteoglycan composition of the zebrafish cornea with that of the human cornea. The similarities between the two species suggest that the zebrafish could serve as a model for investigating the genetics of human corneal development and diseases.
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