Abstract
During lens regeneration in the newt the synthesis of hyaluronic acid increases as iris cells undergo dedifferentiation, and decreases during the redifferentiation phase. In contrast, the levels of hyaluronidase activity which are high in the normal iris remain constant during regeneration (Kulyk et al: Exp. Cell Res., 172:180β191, 1987). We determined whether differential changes in hyaluronidase activity occurred within discrete cell populations of the iris during lens regeneration. In the normal iris hyaluronidase activity was dominant in the iris epithelium, with low levels of enzyme activity being present in the iris stroma. Regionally within the iris, highest levels of enzyme activity were found in the ciliary iris, while lower levels were found in the pupillary iris. Results suggest that a circumferential gradient of hyaluronidase activity decreasing from the dorsal to the ventral regions is present within the iris; superimposed within this gradient, a meridional gradient of enzyme activity increasing from the pupillary to the ciliary region exists. The levels of hyaluronidase activity increase in the dorsal pupillary iris during redifferentiation stages. This activity could be involved in the removal of the hyaluronic acid that is produced during dedifferentiation of the regenerating iris.