A STUDY OF THE JELLY ENVELOPES SURROUNDING THE EGG OF THE AMPHIBIAN, XENOPUS LAEVIS

¹ Department of Biology, Emory University, Atlanta, Georgia 30322

1. The deposition, structure, and composition of the jelly surrounding the egg of Xenopus laevis were studied cytochemically and biochemically. During its passage through the oviduct, the egg is invested with three layers of jelly designated J1, J2, and J3, from innermost to outermost. Particular emphasis was placed on analyzing the layers separately.

2. All layers gave positive histochemical tests for neutral polysaccharides. J2 and J3 stained the most intensely. The sugars present in the polysaccharides of each layer were identified chromatographically. J1, J2, and J3 all contain fucose, glucosamine, and galactosamine. Galactose is present in J1 and J2 and possibly in J3. J3 may also contain mannose or mannosamine.

3. On the basis of the histochemical tests it is suggested that J1 contains sulfate. The weak positive reactions for acid polysaccharides in J2 and J3 indicate the presence of carboxyl groups only. Since no uronic acid was found in the jelly it is proposed that the carboxyl groups are part of amino acids and/or sialic acid which was found in small amounts in all layers.

4. The nitrogen values for the three layers are similar. All layers gave positive histochemical tests for protein although the reactions in J1 were weak and irregular. Treatment of live eggs with proteolytic enzymes showed that all jelly layers do contain some protein as an important structural component and that the protein components of the three layers are not identical.

5. It is suggested that future studies should be concerned with characterizing the macromolecules of the jelly and that, for all investigations of the structure and function of the jelly, the differences among layers should be taken into account.