Fibronectin distribution during cell type conversion in newt lens regeneration.

The distribution of fibronectin during the cell type conversion from iris into lens that occurs in newt lens regeneration was studied by immunofluorescence. Newts were lentectomized and irises at different stages of dedifferentiation and redifferentiation were examined using as a probe a rabbit antiserum prepared to Xenopus plasma fibronectin. In the normal iris, fibronectin is predominantly located at the basal surface of the pigmented iris epithelial cells. During activation and early dedifferentiation fibronectin staining is progressively displayed at the basolateral and apical surface of the depigmenting cell, to eventually surround the surface of the dedifferentiated cells. As cells redifferentiate into lens fibers, staining for cell surface fibronectin decreases and is displayed mainly in the nascent lens capsule. Fibronectin deposition may be associated with the formation of intercellular spaces during dedifferentiation. The fibronectin-rich extracellular matrix could be important in cell reprogramming.