Further Experiments on the Grafted Eye and the Regeneration of the Lens in Amphibians

Abstract

These studies are another part of a series of investigations which have already been reported 1-4 on the grafted vertebrate eye. The present one is based upon results obtained in 262 operated eyes in an adult salamander, Triturus viridescens. In 110 cases the eye was excised and reimplanted in its orbit, i. e., replaced in its normal environment. In 90 cases the lens was removed through an incision made in the cornea. In 62 cases the main blood vessels leading to the eye were severed either along with or without the optic nerve. In a majority of animals the eyes and lenses were measured and dissected in the fresh state.

When the eye is reimplanted there is some reduction in its size followed by a degree of recovery. Careful measurements of the fresh eye show that up to 365 days there is no complete recovery.

Cases vary from 85% to 98% of attaining their normal size during this time. In the specimens from which the lens was removed there was also a slight decrease in the size of the eye following operation. This, however, proved to be only temporary, for there was complete recovery by the 120th day.

When the eye is reimplanted the lens disintegrates as shown in previous experiments on adult amphibians (op. cit.). The new lens in this type of experiment begins to develop from the dorsal part of the pupillary margin of the iris from 18 to 20 days after operation. At the end of 365 days the size of the regenerated lens varies from 72% to 92% of its original measurements. In size the degree of recovery is approximately the same as that of the bulb as a whole.