Cells and organizers.

Abstract

This article evaluates historically some of the factors other than the new “cell biology” that have influenced embryologists to think in terms of cells rather than supracellular agencies. Evidence of Spemann's emphasis on organizers as supracellular phenomena is presented, but it is pointed out that Spemann raised some cellular questions that were by-passed at the time. Vogt and others who studied morphogenetic movements in the 1920's also considered these as supracellular processes, although Vogt previously (1913) had studied the movements of individual amphibian embryonic cells isolated in vitro . It is pointed out that the number of investigators who studied isolated cells in vitro before the development of tissue culture was considerable, including Remak (1855), Stricker (1864), and His (1899), among others. Holtfreter observed the actions of isolated cells from 1931 on, in part, at first, because the cells isolated themselves from cell groups in vitro . His studies of explants, in the 1930's, 1940's, and 1950's, emphasized that supracellular phenomena must be explained in terms of cell properties, including membrane properties. In addition, the dramatic results of his experiments demonstrating affinity drew attention to cells as organized individuals, just as Spemann's experiments had done earlier to demonstrate the integrative qualities of embryos-as-wholes.