Large Glycogen Deposits Research Articles

Cytological development of yolk sac endoderm and protein-absorptive mesothelium in the little brown bat, Myotis lucifugus.

The yolk sac of the little brown bat is unusual in that during the course of gestation both the inner endodermal cells (bordering the yolk sac cavity) and outer mesothelium (facing the exocelom) form simple columnar epithelia which persist throughout gestation. These endodermal cells develop an extensive system of agranular endoplasmic reticulum, numerous lipid droplets and unusual "giant" mitochondria. During development the Golgi apparatus changes position from the apical to the basal side of the nucleus, reversing the polarity of the cells. In general, the endodermal cells have cytological features suggestive of synthetic or secretory activity. The mesothelial cells develop an extensive "absorptive apparatus" in their apices, while large crystalloid-containing granules become numerous in their basal cytoplasm. The mesothelial cells have large deposits of glycogen, especially during mid-gestation, but few mitochondria and little granular endoplasmic reticulum. Endodermal cells do not absorb exogenous protein (peroxidase) even if it is injected directly into the yolk sac cavity. However, placement of peroxidase either in the exocelom or in the maternal vascular system results in the appearance of this protein in the "absorptive apparatus" of mesothelial cells as well as in macrophages in the stroma of the yolk sac. While evidence of absorption was clear, no direct evidence of transport of tracer to fetal blood vascular system was obtained. It is postulated that a major function of the hypertrophied mesothelial cells during gestation is the absorption of proteins and possibly other substances from the exocelomic fluid. The major function of the hypertrophied endodermal cells may be synthesis and secretion of substances into the fetal circulation.

The fine structure of the chinchilla placenta.

The structure of the placental labyrinth, interlobular or "coarse" syncytium, visceral (splanchnopleuric) yolk sac, giant cells and subplacenta of the chinchilla was studied with the electron microscope. The fine structure of the interhemal membrane of the placental labyrinth was found to be hemomonochorial, consisting of a single layer of syncytial trophoblast. In this respect, the placental labyrinth was similar to that of another caviomorph rodent, the guinea pig. The labyrinthine trophoblast had pinocytotic vesicles as well as larger vaculoes and multivesicular bodies. The interlobular syncytium contained granular endoplasmic reticulum, and in one case from early in gestation there were intracisternal granules in the ER. The visceral endodermal cells of the inverted yolk sac placenta had a well-developed system of apical vesicles and tubules as well as larger cytoplasmic vacuoles. Their appearance was similar to that of endodermal cells found in other rodents which are known to absorb proteins and other substances from the uterine lumen. Towards term the giant cells were often vacuolated and contained large deposits of glycogen as well as lipid droplets. The syncytial trophoblast of the subplacenta contained numerous moderately electron-dense granules which may be secretory in function; cytotrophoblastic cells lacked these granules. The subplacental syncytium often surrounded spaces or lacunae which contained an electron-dense granular material.

Pathology of Sarcoptes scabiei infection in pigs : 1. Naturally occurring and experimentally induced lesions

Histological and histochemical alterations were studied in lesions due to Sarcoptes scabiei in the ears of 14 experimentally infected and 16 naturally infected pigs. Large deposits of glycogen and acid mucopolysaccharide were present in both the experimentally induced and naturally occurring lesions. Lesions in the ears of experimentally infected pigs 7 weeks after infection were indistinguishable from those in the cars of naturally infected weaner pigs. Statistically significant increases in mean total protein and in mean beta and gammaglobulin were detected in the sera of experimentally infected pigs. These raised levels were not accompanied by increases in passive haemagglutination titres using a crude extract of Sarcoptes scabiei as antigen.

Carbohydrate cytochemistry of the intestinal epithelium of Ascaris suum. Nature of the microvilli glycocalyx and basal lamella.

Results of various cytochemical tests demonstrate large deposits of glycogen within the intestinal absorptive cells of Ascaris suum. Carbohydrate material is also associated with the microvilli surface and basal lamella. Staining produced by the periodate-thiocarbohydrazide-osmium procedure was abolished by analine or m-aminophenol. Diastase digestion did not alter the staining on the microvilli surface. Similar results were seen using the silver methenamine procedure. A positive reaction was noted on the microvilli surface, vesicles in both the apical and basal cytoplasm, Golgi apparatus, and basal lamella. Lanthanum nitrate stained the microvilli surface and intercellular spaces between absorptive cells. Alcian blue or cetylpyridinium chloride in combination with lanthanum enhanced the staining produced by lanthanum alone. These results suggest the presence of acidic glycans on both the microvilli surface and basal lamella.

Ultrastructural localization of carbohydrate in the hymenium and subhymenium of Coprinus. Evidence for the function of the Golgi apparatus.

The role and distribution of the Golgi apparatus has been compared in hymenial and subhymenial cells ofCoprinus cinereus using conventional electron microscopic and carbohydrate localization techniques. Basidia at early interphase II of meiosis possessed numerous single Golgi cisternae. Golgi vesicles may contain fibrous granular material similar to basidial and basidiospore walls. Vesicles similar in size and apparently in content to those on cisternae accumulated at the growing apex of the young basidiospore. Golgi vesicles were also found in cystidia but appeared to be absent in other cells studied. Pseudoparaphyses, cystidia and subhymenial cells contained large deposits of glycogen which were removed enzymatically in light microscope preparations, but carbohydrate staining persisted in the cytoplasm of basidia, cystidia and basidiospores at the probably sites of Golgi vesicles and cisternae after enzymatic digestion. Septal pore caps of subhymenial cells were surrounded by a fibrillar cytoplasmic zone devoid of cell organelles except ribosomes. The periodic acid-silver hexamine and silver protein techniques for ultrastructural localization of carbohydrates were compared; the latter gave specific results with the controls used. Carbohydrates were localized in certain wall layers of the immature basidiospore and in the contents of Golgi vesicles. Staining also occurred in glycogen, plasma membrane and lomasomes. In the septal pore apparatus staining occurred only in the septal wall and a region in the septal pore swelling probably containing fibrils. The wall of the pseudoparaphyses stained more than the basidial wall. The results suggest that carbohydrates accumulate in Golgi vesicles attached to cisternae, that changes in vesicle contents occur during migration to the basidiospore, and that these vesicles may transport polysaccharides and mucopolysaccharides to the developing basidiospore wall.

Activity of rat liver enzymes responsible for glycogen metabolism after whole-body irradiation

1. 1. The activities of liver enzymes involved in the breakdown and synthesis of glycogen have been investigated in this study after whole-body exposure of rats to 1200 rads of X-ray of mixed gamma-neutron radiation. 2. 2. It was found that glycogen phosphorylase and amylo-1,6-glucosidase (debranching enzyme), both of which are involved in the breakdown of glycogen to “glucose” units, are inhibited by both qualities of radiation. A considerable inhibition in the activity of amylo-1,4→1,6 transglucosidase (branching enzyme) was also observed. In contrast, it was found that the activity of UDPglucose-glycogen transglucosylase which is responsible for the in vivo synthesis of 1,4-polysaccharides is enhanced whether the animal received X-rays or mixed gamma-neutron radiation. 3. 3. Electron micrographs verifeid the presence of large deposits of glycogen in liver of irradiated rats 48 h after their removal from the exposure room, although no food was given to these animals following irradiation.

The ultrastructure of the intestine of Ascaris suum larvae.

The intestine of the infective larva consisted of a solid column of seven cells with no lumen. The cells, which seemed to be enzymatically inactive contained large deposits of glycogen and lipid indicating that the intestine probably functioned as a storage organ at this stage.

The fine structure and histochemistry of the fat body in the locust, Schistocerca gregaria.

ABSTRACT A histochemical study of the fat body attached to the male accessory reproductive glands of the mature desert locust shows that most of the fat body is occupied by neutral fat and probably a little acidic lipid. The cytoplasmic strands between the enormous fat globules contain large deposits of glycogen and some protein. An electron-microscopic study of the mature fat body demonstrates that the synthetic machinery within the cytoplasm is sparse : the endoplasmic reticulum is scarce and in the form of isolated and flattened cistemae; there are few ribosomes; the Golgi units are rather rare and small; and the cytoplasmic bodies, which are thought to be derived from pinocytotic vesicles and probably contain precursors for carbohydrate and lipid synthesis, are few in number. Microtubules, of about 200 Å diameter, and each formed as a compact helical structure with a repeating period of about 150 Å, are found occasionally in the cytoplasm. Their function is unknown, but they are found closely associated with mitochondria and lipid globules. It is suggested that little synthesis takes place in the mature fat body since there is little nutrient circulating in the haemolymph, and that at this stage it acts mainly as a storage organ for glycogen and neutral fat.

AN ELECTRON MICROSCOPE STUDY OF THE FETAL DEVELOPMENT OF HUMAN LUNG

Results of a study of lung ultrastructure in 13 human fetuses of about 1 to 6 months of gestation are reported. Light microscope controls were obtained in all cases. The columnar epithelial cells of young fetuses contained large deposits of glycogen which tended to become less abundant between the fourth and the sixth month. The fine structure of epithelial glycogen is described. A gradual transition between the columnar or cuboidal epithelium and the attenuated cytoplasmic lining of fully developed alveoli started during the fifth month, when the first contacts between capillaries and epithelium were established. Further differentiation of the epithelial cells in two morphologically different types, as observed in adult lung, took place during the sixth month. Both types appeared to have the same endodermal origin. Lamellar inclusions were first observed during the sixth month. Their significance is discussed in the light of recent work on alveolar surface activity.