Biomedical subjects

G Pradal

Publications and source records attributed to G Pradal.

At least 37 records · Page 2Linked to original sources

PubMed1982

Quantitative autoradiography, electron microscopy, and granulometry of endocrine cells in the rabbit colon.

A high-resolution autoradiographic study was conducted on 268 thin sections of endocrine cells in the rabbit colon following injection of (3H) L-dopa. Using quantitative autoradiography, silver-proteinate impregnation, granulometry, and statistical analysis of cell populations by the Falck procedure, three cell types were identified--EC, L; and H--as well as a single cell with distinct ultrastructural characteristics. For the first time, a fine quantitative estimation of the handling ability of amine precursor related to the cross-sectional areas of each cell type was obtained, using a Kontron Digiplan image analyzer. All cells studied showed the ability to take up the precursor. Labeling indices were 6.63, 2.15, and 2.14 for EC, L, and H, respectively. These data and silver-proteinate impregnations provide good criteria for differentiating EC from H cells despite morphological similarities. After critical analysis of granule diameters, L cells were considered to be pluripotential in secretory activity.

Animals↗

PubMed1980

A simple impregnation technique for thin and semithin enterochromaffin cells in sections.

Constant, intense and precise impregnation of enterochromaffin (EC) cells was achieved simply by floating thin or semithin sections of gut mucosa, fixed in osmium tetroxide or in glutaraldehyde with postfixation in osmium, on a silver nitrate or proteinate solution. EC cells alone showed impregnation in the light microscope. In the electron microscope, impregnation affected not only the secretory granules of EC cells but also, although much more faintly, those of other, non-EC cells (D, X, D1, G and other cells). Lysosomes also showed partial or total reactivity. Oxidation reduced but did not entirely suppress EC cell staining and had no effect on non-EC endocrine cell staining. Since the reaction did not occur with glutaraldehyde alone, osmium appeared to be a crucial component of the process. These findings should be borne in mind in applying Thiery's method for vicinal glycol groups to the type of study material used in these experiments.

Animals↗

PubMed1980

Application of the thiocarbohydrazide method for vicinal glycol group detection to the study of gastric mucosa endocrine cells.

The thiocarbohydrazide-silver proteinate (TCH SP) method was applied to the study of cat, rabbit and mouse gastric mucosa endocrine cells. After 24-h treatment with thiocarbohydrazide (TCH), glycogen was seen in the hyaloplasm of X, D, P, A and O cells but not in EC, EC-like or D1 cells. With flotation times as short as 30 to 40 min glycogen was readily detected in X cells. Secretory granules of EC cells were constantly stained, while those of D1 cells failed to react. In most experiments granules of X, A and O cells showed peripheral "staining", while in others staining of variable intensity affected the entire granular cross-section in X, D and P cells. With 72-h exposure to TCH, EC and EC-like cells showed particles resembling glycogen, even staining or only peripheral staining of certain EC cell granules. From the results of this and previous studies, EC cell staining is believed to be due wholly or partly, according to exposure times, to the action of silver proteinate, while that of certain non-EC cells is probably a specific indicator of complexed carbohydrates.

Animals↗

PubMed1977

[Cytochemical study of intestinal endocrine cells in rabbit fetuses during in vitro induced degeneration and differentiation (author's transl)].

Ontogenic differentiation of intestinal serotonin cells of 22 days old rabbit fetuses were studied in vitro. After 3 days of organotypic cultivation in solid medium, a great part of epithelial cells became necrotic and were eliminated into the lumen while a first flattened, then cuboïdal, then prismatic new growed epithelium in which FIF indicated some serotonin cells was present. Comparison of pictures obtained on the same slide by different methods was used in order to estimate correspondances between amine storage, argentaffin, argyrophilic and reductive properties. A new phase in serotonin cell differentiation was readily distinguished since young cells successively yeilded FIF, later argyrophilia, later argentaffinity. These datas, at variance with that occurs in vivo where FIF and argyrophilia appeared simultaneously, give a new criteria for differential mechanism studies, disprove the theory of an amine induced argyrophilia and enhance the hypothesis of a hyaloplasmic amine storage in very young cells.

Animals↗

PubMed1976

[Ultrastructural identification and immunocytochemical study of somatostatin cells in antral mucosa of the rabbit and the mouse (author's transl)].

In normal and L-Dopa treated rabbits and mice, combined immunochemical methods, photonic histological methods for endocrine cells and ultrastructural methods were used to elucidate ultrastructure and properties of somatostatin cells of the antral mucosa. In normal rabbits, immunoreactive cells giving no fluorescence with Falck's technic, they corresponded neither to serotonin cells nor gastrin cells; they were unreactive with Fontana, Hellerström-Hellmann, Sevier-Munger and Mac Conaill methods but very slightly stained with Grimelius methods. In L-Dopa treated animals somatostatin cells gave formaldehyde induced fluorescence (they were included in GIC cells, thus in Apud group), exhibited a good reaction with Grimelius and Sevier-Munger methods. In order to carry out the alternate semi-thin/thin section procedure (semi-thin sections for immunofluorescence or immunoenzymatic detection and serial thin sections counter-stained for conventional ultrastructure studies), immunological treatment were performed on M.F.F.--glutaraldehyde fixed small fragments of mucosa before inclusion in Epon 812 or, after inclusion, on semi-thin sections. We succeeded in identifying ultrastructurally somatostatin cells. They displayed round or ovoïd shaped secretory granules, and three constant typical structures: numerous microfilaments--light and homogenous granules, often seeming like lipids---granules made up by coarsely filamentous cores surrounded by a large empty halo. Somatostatin cells seemed different of X cells because of their predominant localisation in the antral mucosa (in the rabbit X cells were predominantly in the fundus) and because of the lack of nuclear microfilaments; they also seemed ultrastructuraly different of D1 cells.

Animals↗

PubMed1976

[Coexistence of reactive and nonreactive endocrine cells in the fundal mucosa in the rabbit].

Whether the same endocrine like cells are reactive towards different staining methods has been examined in normal and L-Dopa treated rabbits for distinction of cell types. Correlation with electron microscopy is proposed. It seems likely that SM cells (poorly reactive with Sevier-Munger technic) include two cell types: cells having around medium size and dense granules; cells having small round dense granules (D1?). X cells may correspond to a well defined group at the electron or photonic microscopic level. Insertion of D cells (according to Solcia and coworkers nomenclature) is not satisfactory but true non Apud cells are described. The signification of Jt (dim yellow) cells remains unknown.

Animals↗

PubMed1975

[Ultrastructural and cytochemical study of the endocrine serotonin secreting cells of the fetal and adult rabbit intestinal mucosa].

Endocrine cells of intestinal mucosa have been studied in rabbit fetuses and adults. The problem of an ultrastructural identification of "preargentaffin" serotonin cells has been elucidated comparing cytochemical and ultrastructural datas. Since all cells exhibiting a yellow formaldehyde-induced fluorescence reacted with Sevier-Munger method and since all impregnated cells were fluorescent it has been concluded that impregnated cells at the electron microscope level are serotonin cells; these cells had generally small and round granules. Another cell type with small round granules showing deposition of silver grains on the outer rim has been identified as granular S cells.

Animals↗

PubMed1975

[Quantitative study of serotonin-containing cells in fetal rabbit duodenum].

In order to attempt identification in vitro of parameters involved in the cellular differenciation, it was necessary to possess a standard material with identical content and distribution of serotonin cells; these two properties are investigated in this paper. Falck's technic is the only sensitive and specific method in demonstrating serotonin young cells devoid of argentaffinity. From 21, 22, 23 and 25 days old rabbit foetuses, 10 mm length duodenal pieces were treated according to Falck and sections serially cut at 8 microns. Some of these specimens were divided prior to Falck treatment in two pieces 3 mm away from the pylorus and in each piece 200 paraffin sections were cut at 8 microns beginning by adjacent ends and progressing in opposite direction. The number of EC sections in 400 whole transverse sections were determined for each foetus. Great variations were observed from one foetus to another, along the intestine, with weight and age. The Student-Fisher test applied to two consecutive pieces of the same duodenum gathering foetuses in groups of 5 animals did not show significative differences from a group to another. Thus, this material can be employed for comparisons under experimental conditions.

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PubMed1974