Metabolic Properties of the Regions of the Amphibian Gastrula

Abstract

A number of authors have investigated the oxygen consumption and carbon dioxide production of the amphibian embryo at various stages of its development, with results of considerable interest. But such investigations throw no light upon the properties of the individual regions of the embryo at various stages, although the work of experimental embryologists has furnished us during the last 20 years with fundamental information about these regions and the part they play in the morphogenesis of the organism. In particular, the phase of gastrulation, during which are formed the germ-layers of classical embryology, and which involves the action of the primary organiser in determining the main axial structures of the embryo, merits the closest study. Only recently have sufficiently delicate chemical methods become available for attacking this problem. Since Rehberg developed the first ultra-micro burette, these methods have been greatly extended by the work of Linderstr⊘m-Lang, Holter, and their collaborators at Copenhagen. The first application of this kind of technic to the metabolism of the gastrula was made by Heatley, who estimated the amounts of glycogen in the various regions of the gastrula and confirmed by direct chemical analysis the specially marked disappearance of this polysaccharide during the invagination of the roof of the archenteron, through the dorsal lip of the blastopore. All such observations have significance since it is in the dorsal lip of the blastopore and nowhere else during normal development, that the organiser “hormone” is liberated from its inactive combined form. Wishing to study the metabolic properties of the dorsal lip of the blastopore, as opposed to the ventral ectoderm, where the organiser is not normally liberated, by manometric means, we found in the Cartesian Diver ultra-micro-manometer a very suitable tool.