SPATIAL AND TEMPORAL VARIATIONS IN EXTRACELLULAR-MATRIX OF PERIOCULARAND CORNEAL REGIONS DURING CORNEAL STROMAL DEVELOPMENT

The development of the avian corneal stroma occurs in discrete develop mental stages. During this sequence of events, the neural crest-derive d corneal fibroblast precursor cells are surrounded by distinct extrac ellular matrices which change both spatially and temporally. To elucid ate the role of these matrices, extracellular matrix components in the periocular mesenchyme and cornea were analysed prior to and during mi gration and differentiation of corneal fibroblasts using antibodies ag ainst collagens, proteoglycans and glycoproteins. Previous work has co ncentrated on the matrix of the corneal stroma rather than the matrix of the periocular mesenchyme. Since the precursors of the corneal fibr oblasts are present within and must migrate through the periocular mes enchyme prior to entry into the cornea proper, this environment was fu lly evaluated. The present study documents the matrix composition of b oth the cornea and periocular mesenchyme at developmental stages that are prior to and after initiation of corneal invasion by the corneal f ibroblast precursors, Variations in matrix molecules comprising both t he periocular mesenchyme and cornea were demonstrated. These include c hanges in the distribution of collagen types I, II, III, IV and VI; th e proteoglycans decorin and lumican; as well as the adhesive glycoprot eins tenascin, fibronectin and laminin. It is hypothesized that the va riations in matrix localization are important in the regulation of cel l migration and differentiation during normal corneal development. Any regulation is likely to involve a combination of components found in the extracellular matrices and therefore, a consideration of the matri x rather than isolated components is required. (C) 1996 Academic Press Limited