HISTO- AND CYTOCHEMICAL STUDIES ON THE SUPERFICIAL LAYER OF YOLK PLATELETS IN THE TRITURUS EMBRYO.

Summary Histo- and cytochemical investigations designed to identify the substances constituting the superficial layer of yolk platelets in the embryonic cells of Triturus pyrrhogaster were carried out. The border of the platelets, where the superficial layer is present, showed an intensive affinity to toluidine blue. The stainability was not affected by treatments which were supposed to remove RNA. Using the ultraviolet photomicrography, it was found that the absorption value was higher at E 280 than at E 265 in any region of the platelet. Both portions of the platelets showed a negative reaction to the Feulgen staining. The border of the platelets reacted positively to PAS, alcian blue, and Hale. No difference could be found in sections previously exposed to salivary amylase or hyaluronidase. The basophilia in the border of the platelets remained unaffected by lipid-extracting treatment. A presence of some acid polysaccharides in the superficial layer of yolk platelets seems to be the most probable explanation of the findings described in this paper. Our findings were discussed in comparison with some conflicting results reported previously from other laboratories.