A comparative cytochemical study of the yolk platelets in the growing oocytes of Triturus cristatus and Rana esculenta.

Recent cytochemical techniques for the detection of proteins, neutral and acid mucopolysaccharides, lipids and phospholipids in the yolk platelets of the growing oocytes of Rana esculenta and Triturus vulgaris are employed. Cytochemical analysis showed that the yolk in the form of granules or platelets, in the constituting itself the most prominent cytoplasmic inclusion of amphibian eggs, contains a protein moiety consisting of individual typical amino acids lacking tryptophan in Triturus, a carbohydrate fraction consisting of neutral mucopolysaccharides distributed in the superficial layer of each platelet, and phospholipids, phosphoproteins and lipoproteins which are present only in the main body of the same platelets. The different amino acid composition indicated a protein heterogeneity which could be connected with the tissue incompatibility of the transplantations when these last were effected between the orders Urodela and Anura. The different protein composition of the yolk also can be reflected at the species-specific level. The cytochemical data are further reviewed with the mode of utilization of the yolk platelets.