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Biomedical subjects

J Gouranton

Publications and source records attributed to J Gouranton.

33 records · Page 2Linked to original sources
PubMed1976

Observation on intranuclear crystal and nucleolar size at different stages of cell differentiation in the midgut epithelium of several insects.

Based on an inverse size relationship between nuclear crystal and nucleolus in different cells it has been postulated by several authors that the crystal develops from nucleolar materials. The purpose of the present paper is to investigate the validity of this argument. Intranuclear proteinaceous crystals appear in differentiating midgut cells of Gyrinus marinus and Tenebrio molitor. In an autoradiographic study we have previously demonstrated in these two species that the crystals do not develop from nucleolar materials. However, an inverse relationship with regard to size is observed between these 2 structures during the cell differentiation: the cross-sectional area of the nucleolus decreases when the cross-sectional area of the crystal increases. But a decrease in size of the nucleolus is also observed during the differentiation of the midgut cells of Gyrinus natator where the crystals are not present. Consequently an inverse size relationship cannot be a sufficient argument to postulate that intranuclear crystals and nucleoli are interconvertible structures; decrease in size of the nucleolus is not related to development of the intranuclear crystal.

Animals↗
PubMed1968

[Composition, structure and mode of formation of mineral concretions in the midgut of the Cercopid (Homoptera)].

The granules which occur in the cells of a part of the midgut wall in Cercopid larvae and adults (Homoptera) have been studied by biochemical and cytochemical methods and by electron microscopy. The granules have a diameter up to about 2micro and contain calcium, magnesium, iron, carbonates, and phosphates. Protein and acid mucopolysaccharide have also been detected. A chromatographic study shows that uric acid and guanine are not present. The young concretions occur primarily in ergastoplasmic cisternae. They are first wholly electron-opaque, but their center becomes more and more clear. In very old spheres, only a thin shell of electron-opaque material remains. The spheres which have reached about 1micro in diameter are all associated with myelin figures. The granule-containing cells, which nearly occlude the lumen of the midgut in larvae, are eliminated in the very young adults, but the storage excretion still continue in adults.

Animals↗