The fate of amphibian regenerating blastema implanted into lentectomized eyes

Abstract

AbstractTail blastemas of larval anurans and urodeles were implanted into 106 lentectomized larval eyes to test claims that lenses develop from blastemas in an eye environment. None of these eyes regenerate a lens from the dorsal iris. Lentectomy was complete in all 35 Amblystoma tigrinum, in 34 of 36 Rana pipiens and 21 of 35 Rana clamitans eyes.After complete lentectomy, blastema grafts formed spherical masses of mesenchyme cells sometimes enclosed in epithelial vesicles, but never associated with lens fibers. Lens fragments not removed were easily identified. They were usually fused with the blastema. Their appearance was the same from one to many days after implantation.Leg and tail blastemas were implanted into 64 completely lentectomized adult Triturus viridescens eyes which regenerate a lens from the dorsal iris. The grafts formed spherical compact groups of epithelial and mesenchyme cells, loose cultures of cells and fibers, or cartilage and muscle, but never lens fibers. One of 13 brain segments implanted into lentectomized newt eyes carried dorsal iris cells on its surface. They formed a small lens gving a false picture of blastema origin.From an analysis of the literature and of the results of these experiments it is concluded that the claims so far made for lens formation from blastema cells are an incorrect interpretation of a mere fusion of lens fragments and implanted tissues and that regenerating tissues of anurans and urodeles are not competent to form lens as has been claimed.