Date of Award

Spring 1965

Document Type

Thesis

Department

Life & Environmental Sciences

Abstract

The phenomenon of the migration of cells is of unrivaled importance throughout the metazoans, as it is a basic process in embryonic development, wound healing, the growth of tumors, and many other events both essential and harmful to life. This paper deals with a special aspect of migration, the migration and reaggregation of cells separated from one another by mechanical or chemical means, and the consequent re-formation of the histological structure of the whole organ or organism from which the cells were derived. Dissociated cells from a variety of organisms have been worked with, these donor animals ranging from the simple sponge to parts of many embryonic and adult vertebrates in complexity. Most of the success in the field, however, has been in experiments with either embryonic or very primitive cells; only in the case of the adult frog, has there been any real success in the reaggregation of the cells derived from the adult of a highly complex form.

The reaggregation of sponge cells dissociated by expression through a fine mesh was one of the earliest discoveries in the field, occupying the time of many investigators from 1907 to the present time. Wilson, who published works on the subject from 1907 to 1925, was the pioneer in this area, but he was soon followed by a myriad of others interested in this amazing property of the cells of the sponge, among whom were Huxley, Muller, Galtsoff, Peehy, and most recently Ganguly. Wilson and Huxley maintained that cells after dissociation de-differentiated, i.e. attained a generalized state in which they lost their previous morphogenetic characterisitcs. On regeneration of the organism, the cells may return to their original state, or re-differentiate into an entirely different type. On the other hand, Galtsoff felt that, except for a few "totipotent" cells, most the the cell types maintained their identities throughout the process of regeneration. These early workers concerned their studies only with the activities of the regenerates from 24 hours onwards.

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