Secondary lens formation caused by implantation of pituitary into the eyes of the newt, Notophthalmus

Whole pituitary glands, as well as equivalent-sized pieces of kidney, liver, and adrenal tissue, were implanted into the anterior chamber of the adult newt eye. Secondary lens formation was present in 16 out of 17 cases of the pituitary implantation experiments in which the pituitary tissues were exposed to the anterior chamber fluid. In only one case out of 23, did another implanted tissue (liver) stimulated secondary lens formation. The extent of secondary lens formation was correlated with the position (closeness) of the implant in relationship to the dorsal iris. In all cases of secondary lens formation from the dorsal iris stimulated by tissue implants, the polarity of the developing lens was reversed so that the pole of the fiber axis was directed toward the implant rather than the retina. It appears that the ectopic pituitary produces a diffusible substance capable of initiating lens formation from the dorsal margin of the iris and capable of determining the orientation of the fiber axis pole of the developing lens.