Proteoglycan distribution in developing rabbit cornea.

We used a staining procedure specific for sulfated glycosaminoglycans, cuprolinic blue dye (CBD), and immunohistochemical techniques to determine the histological distribution and ultrastructural organization of proteoglycans in developing rabbit cornea. We found several types of CBD-stained structures located throughout the corneal stroma, indicative of the distribution and perhaps the chemical heterogeneity of proteoglycans in this tissue. Keratan sulfate-specific immunohistochemical evidence supports our cytochemical findings. Our results suggest that low-sulfated keratan sulfate proteoglycans are found throughout most of the developing stroma, with the exception of the posterior margin of this tissue. Highly sulfated keratan sulfate proteoglycans in young fetal corneas, initially restricted to the subepithelial stroma, progressively extend to deeper portions of the stroma with development. Dermatan sulfate proteoglycans are located throughout the stroma, including the posterior margin. Invoking a recently published "oxygen-lack hypothesis" and correlating the tissue location of proteoglycans with the source of oxygen, we hypothesize that the distribution of proteoglycans in the developing rabbit cornea is related to the selective synthesis of keratan sulfate glycosaminoglycans under hypoxic conditions.