HISTOCHEMICAL-LOCALIZATION OF HYALURONIC-ACID IN VITREOUS DURING EMBRYONIC-DEVELOPMENT

PURPOSE. TO determine the chronology of the appearance and localizatio n of hyaluronic acid (HA) in mouse vitreous during the embryonic and e arly postnatal stages of development and in human vitreous during earl y embryonic development.METHODS. A histochemical method using the spec ific affinity for HA of a bovine cartilage proteoglycan was used on mo use eyes at embryonic (11 to 18 daps) and early postnatal (8 and 18 da ys) stages. The same technique was applied to human embryonic eyes of 6, 8, 9, and 10 weeks. RESULTS. In the mouse, HA is detected early (12 -day embryo stage) in the equatorial vitreous and in the internal port ion of the corresponding retinal epithelium, behind the anterior rim o f the optic cup. Later in development, HA staining extends temporarily to the posterior vitreous and to the internal layers of the posterior retinal epithelium. In human embryos, HA staining is clearly visible in the posterior vitreous and in the equatorial vitreous, where it is more intense at all the developmental stages. From the 8-week stage on ward, the internal layers of the developing retina are also heavily st ained. CONCLUSIONS. HA appears very early in developing vitreous of mi ce and humans, and staining is observed first and predominantly in the equatorial portion of the vitreous. In contrast to human embryos, HA staining in the posterior mouse fetal vitreous is only faint and trans ient. In both species, staining of the internal layers of the retinal epithelium is detected in the presumptive ciliary body region and in t he more posterior retina. The observed temporal and regional simultane ous localization of HA staining in the vitreous and the internal layer s of the retinal epithelium is suggestive of a possible role for these cells in the production of the molecule.