On the Periodic Acid Schiff Positive Substance of Anuran Retina and Its Relation to Development

抄録

A) Lillie(1952) reported that the saliva-insoluble PAS positive substance in the outer segments of the retinal rods would be a -glycolipo-protein complex. When fixed with Zenker-formol, the substance is negative or slightly positive to the PAS reaction. Whereas, after acid hydrolysis PAS staining calls forth strongly positive reaction of the outer segments, showing the strongest coloration of the fixatives which the author used (Figs.1 and 2). This phenomenon was analyzed, using the toad's retina as material.
1) Such a phenomenon has been observed only in the fixatives which contained mercuric chloride.
2) In addition to thepositve PAS reaction, positive lead tetraacetate Schiff reaction, blocking andunblocking of these reactions by acetylation and deacetylation respectivelyafter acid hydrolysis, as well asnoinhibition of the reactions by deamination, indicate that thesubstance contains 1-2 glycol linkages.
3) The lead tetra-acetate reaction of the substance in question after hydrolysis is inhibited by incubation in saturated mercuric chloride solution only in the sections fixed with Zenker-formol. Such was not the case with the Regaud's fixative. Chemical pure glycolipid, smeared on the slide glass, behaves in a similar manner to the fixed retinal substance. These experiments suggest possible physicochemical interaction ofHgCl2 with glycolipid.
B) The development of visual cells is described from the standpoint of the histochemical behavior of glycolipid and glycogen during differentiation.
1) The visual cells in tadpole stage are the early forms of rods, although all of them possessed conical outer segments, while the cones themselves may be differentiated during metamorphosis. Such a conclusion, being different from those of the hitherto known investigations, does not correspond to G. Wald's chemical findings asfollowing: the porphyrosin-vitamin A2 system of visual organ of anuran tadpole transfers completely to rhodopsin-vitaminA1 system during metamorphosis (Wald,1946,1952).
2) The outer segments of both rods and cones in their early developments are stained with the Heidenhain's iron hematoxylin but not stained with PAS reaction. By such stainability of visual cells, especially of cones during metamorphosis, it is confirmed that the visual cells in tadpole stage are rods.
3) Glycogen appears in nuclei, ellipsoids and foot regions of developing rods and disappears in the commencement of metamorphosis. These appearances of glycogen coincide with the stage of differentia- tion of rods, especially of their outer segments. The author considers that glycogen participates as an intermediate metabolite in the synthesis of lipid in development of the outer segments of rods.