Date of Award

Spring 1959

Document Type

Thesis

Department

Life & Environmental Sciences

First Advisor

James Manion

Abstract

Self-repair characterizes all protoplasm.Every species of animal is capable, at least to some degree, of replacing lost body parts, and in most cases, do so with unvarying accuracy. Either in part or in whole, the new structure assumes the characteristics of the old, both in structure and function. This unique power of the body, called regeneration, offers a splendid opportunity to observe the basic features of cell division, growth, and differentiation. Very obvious in its outward manifestation yet very involved in its fundamental aspects, regeneration has been the subject matter of much research in the past few years. One of the more notable things about this phenomenon, despite its occurrence in all living things, is the fact that the regenerative capacity tends to vary 2 inversely as the scale of organization. Generally, the lower animals on the phylogenetic scale can replace lost parts better than the more highly developed organisms which rank above than. Hence, much investigation has been undertaken to determine the prerequisites for regeneration, and although the source of the regenerating cells can be accurately pin-pointed in many species, there are different theories as to what curbs the regenerative processes in higher animals. In spite of the vagueness regarding the controls directing regeneration, there still remains this fact - some organisms are good regenerators, others are not. Among the higher forms that regenerate rather well are the 1 amphibians. During their larval stages, regenerative power is very high, and in urodeles, it persists even after metamorphosis. For example, when the limb of a newt or salamander is cut off, immediately cells migrate and are mobilized in the wound area. Del1 division begins and soon a white, cone-shaped blastema appears. The blastema elongates, and presently several tissues of a normal limb become differentiated. After a period varying with the age and state of the individual and with the conditions of the environment, a fairly typical limb is found in the place of what had been an amputation stump. This same situation occurs in the tadpole larva of the frog. Here, on large scale, is cell division, growth, and differentiation, an excellent opportunity to study the controls which operate regeneration. Also, the effects of various chemicals, heat, light, PH, and other factors which influence development can be investigated.

Share

COinS