Control of lens cell differentiation and ion fluxes by growth factors.

The results of these studies suggest that an insulin-like growth factor, lentropin, present in the vitreous humor of the eye, is responsible for stimulating lens epithelial cells to differentiate into lens fiber cells during normal lens growth. Lentropin has been shown to stimulate embryonic lens epithelial cells to elongate, specialize for the synthesis of delta crystallin, the major protein synthesized in chicken embryo fiber cells, and to cease DNA synthesis and mitosis. Lentropin appears to decrease the permeability of the plasma membrane to potassium and, by this mechanism, may cause lens fiber cell elongation.