Localization of Glycogen in the Cestode, Hymenolepis Diminuta

Glycogen isolated from the rat tapeworm Hymenotepis diminuta by a mild quantitative procedure exhibits a sedimentation coefficient distribution characterized by two distinct regions of molecular weight with mean S values of 200 X 10-13 cm/dyne, see and 1500 X 10-13 cm/dyne, see respectively (17). This distribution is characteristic for the physiological state of the organism, and differences in the incorporation of '4C-glucose into both the high and low molecular weight components as a function of glycogen level have been observed (8). These two components may be synthesized independently from each other or interconversion may occur. A consequence of such an interconversion would be the presence of both the high and the low molecular weight glycogens within the same cell. Glycogen particles can be identified by electron microscopy in sections of intact tissues stained with lead salts at alkaline pH (11, 15, 19). Although this reaction is not specific and its mechanism is not understood (10), the results obtained with it in several tissues agree with histochemical and biochemical data (1, 2, 18) This report deals with some observations on the localization of glycogen in the parenchyma I of H. diminuta by electron microscopy and with a The term "parenchyma" as defined in The Zoology of Tapeworms parasitology: "a loose sponge-like mass of tissue, enclosed by the skin, within which are embedded the muscle, nerves, osmoregulatory organs and reproductive organs." some aspects of its cytological organization which are relevant to the interpretation of the results. MATERIALS AND METHODS Glycogen was isolated and characterized by the cold water procedure of Orrcll and Bueding (6, 16). It was determined by a specific micro-enzymatic method (4, 5) and all concentrations arc expressed as per cent glycogen per g wet weight of worm. The tapeworms were obtained from rats 10, 16, and 19 days after infection with 10 cisticercoids per rat. The worms were removed as already described (8, 9) and immediately immersed in chilled fixative after a brief rinse in Krebs-Ringer bicarbonate medium (9). Immature , mature, and pregravid proglottids according to the terminology of Fairbairn (9) were studied. The fixative was either 1% osmium tetroxide or 6.25% glutaraldehyde in 0.1 M phosphate buffer pH 7.3 containing 0.001 M Ca and Mg. The glutaraldehyde-fixed tissues were postfixed in osmium tetroxide after overnight rinse in the same buffer containing 0.1 M sucrose. They were dehydrated in ethanol and embedded in Epon 812 (13). A few …