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Biomedical subjects

G Grignon

Publications and source records attributed to G Grignon.

At least 73 records · Page 4Linked to original sources
PubMed1980

Ultrastructural study of Sertoli cells in rat seminiferous tubules during intrauterine life and the postnatal period.

Sertoli cells have various functions: mechanical (creation of two compartments in the seminiferous tubules, migration of germinal cells), secretory (secretion of anti-Müllerian hormone, inhibin, androgen-binding-protein and estrogen) and phagocytic. We report an ultrastructural study of the rat Sertoli cell during maturation and consider possible correlations between the acquisition of certain morphological characteristics and certain functions. During fetal life, the Sertoli cell possesses differentiated zones of junction with the gonocytes and seems to have a role in the migration of the gonocytes towards the periphery of the seminiferous tubule. The Sertoli cell performs the phagocytosis of the gonocytes which degenerate during their migration, and seems to be the site of production of protein granules, whose presence can be related to the synthesis of anti-Müllerian hormone. After birth and before puberty, when the inclusions resembling secretory granules disappear, the Sertoli cell membranes in contact with spermatocytes II and spermatids differentiate, forming, through the differentiated junctional complexes, two compartments (adluminal and luminal) in the seminiferous tubules. Finally, they acquire the characteristics of active secretory cells, capable, in particular, of steroid synthesis.

Animals↗
PubMed1980

[Type III pneumocyte. The alveolar brush-border cell in rat lung. Study by transmission electron microscopy (author's transl)].

The type III pneumocyte or alveolar brush-border cell was studied in the normal adult rat by transmission electron microscopy. The observation of thick sections and the technique with alcian blue-lanthanum nitrate gave precisions on the fine structure of this cell by revealing the existence of pinocytotic micro-vesicles, of basal ergastoplasm and the proximity of unmyelinated nervous fibres. The different morphological data were confronted with the hypothesis of this cell playing an alveolar chemoreceptive part. Different appearances of the cell body of the type III pneumocyte suggest on the other hand contractile properties of a not well known determinism. Present data concerning the origin of this cell are discussed.

Animals↗
PubMed1979

[Serotoninergic innervation of the paraventricular organ in chick embryo and chick; histofluorescence and autoradiography study optic and electron microscopy].

Fluorescence microscopy (Falck and Hillarp technique) of 11th day old chick embryo shows aminergic neurons and processes in the paraventricular organ area. Administration of tritiated amines permits us to observe uptake and storage of serotonin only as early as the 10th day; this suggests a very early hypothalamic serotoninergic nervous system differentiation.

Animals↗
PubMed1978

An autoradiographic study on the biosynthesis of the capillary basal lamina in the chick embryo telencephalon.

The elaboration of the basal lamina of telencephalic capillaries has been studied by autoradiography in chick embryos from day 16 to 19 of incubation. The cerebral vascular basal lamina is actively synthesized during the period of these stages of development. The animals were sacrificed 2, 15, 40 and 180 min after intravenous injection of 3H-proline. The hydroxylation of proline to hydroxyproline in the "secretory" cells permits their identification. Our observations suggest that endothelial cells, pericytes and perhaps glial cells participate in this elaboration. The various stages of the synthesis are performed sequentially in the ergastoplasm and then in the Golgi apparatus before the secretory material is released by exocytosis.

Animals↗
PubMed1978

[Effect of diphenylhydantoin administered during gestation and lactation on the motor development and cerebellar histology of the young rat].

Rattus norvegicus females were treated by diphenylhydantoin (D.P.H.), all along pregnancy and lactation. 4 groups were constituted: a 100 mg DPH/kg/day group, a 50 mg DPH/kg/day group; a placebo group (treated with pure water), and control group. D.P.H. was given twice a day by a gastric tube. The cerebellar Purkinje cells studied through light microscopy and transmission electron microscopy in young rats (25 days old) showed no visible alteration. 2 motorcoordination tests were applied to the young rats, during their 2nd and 3rd weeks of post-natal life. Young rats of DPH 100, DPH 50 and placebo groups showed a backwardness relatively to control. This backwardness may be attributed to the maternal forced feeding stress, but not to a specific action of the DPH.

Animals↗
PubMed1976

[Gastric mucosa in patients with rheumatoid polyarthritis treated by anti-inflammatory agents. Clinical, radiological, endoscopic, anatomopathological and ultrastructural study].

One hundred patients (50 male, 50 female) suffering from rheumatoid arthritis, treated for more than 6 months with steroid and/or non-steroid anti-inflammatory agents were studied using barium X-rays and gastro-fibroscopy. In 69, one or more gastric biopsies were taken during the endoscopy. The study showed a marked preponderance of ulcerous lesions in males, 9 of the 13 iatrogenic ulcers being found in this sex. It also confirmed the frequency of gastritis and the absence of any correlation between clinical signs and radio-endoscopic findings as well as between the latter and histopathological data. An ultra structural study carried out in 20 cases revealed focal lesions of the clear cells of the neck of the fundus and antral glands and, in 4 cases, marked changes in the gastric endocrine cells.

Anti-Inflammatory Agents↗
PubMed1976

[Ultrastructural study of the follicular cells of the adenohypophysis of the chicken].

As in other species, a network of follicular cells linked together by functional complexes can be observed by electron microscopy in the adenohypophysis of the chick. No secretory granules are seen in the follicular cells. They are connected with each other by thin and long processes inserted between the glandular cells and the perivascular spaces. They limit, by their follicular pole, submicroscopic cavities of irregular size and shape. They are empty or occupied by a material of variable density. These cells exist very precociously in the embryo but their characteristic organisation to form a network is observed only on the 16th day of incubation. Our experimental study made it possible to evoke, as a number of other authors, that they play a role in the functions of support, exchange, transport of secretory material or phagocytosis.

Animals↗
PubMed1976

[Changes in the adrenocortical cells of the chick embryo after treatment with corticosterone or graft of a functional adrenal].

The ultrastructural changes of adrenocortical cells of the chick embryo, caused by administration of corticosterone or after grafting of an additional adrenal gland to the host chorio-allantoic membrane, were studied. The main cytoplasmic change is an increased amount of dense bodies and complex bodies. Arylsulphatase activity is detected in these bodies which should be included in the lysosome series. It is possible that a lysosomal mechanism may be active in the adrenocortical cells.

Adrenal Cortex↗
PubMed1976

[Activity of blood somatomedin during childhood in normal subjects and in delayed growth].

A hundred sera from children, were used to evaluate normal levels of somatomedin activity and pathological levels. The results showed that the level of this activity in the blood, rises gradually during infancy, to reach normal adult reference level by postulate, equal to 1. Although the values are widely dispersed in each sample, the general phenomenon of their increase in infancy remains significant. The patients with somatotropin deficiency, have very low somatomedin values which become normal under the influence of injection of human growth hormone. A very unusual case is that of Laron's dwarfism with very high values of HGH in the plasma, and very low levels of somatomedin and, clinical and laboratory indifference to injections of exogenous HGH. The prospects of progress in the techniques of study of somatomedin will be of great service in the near future.

Adolescent↗
PubMed1975

Immunocytochemistry of pituitary corticotroph cells in terrestrial turtle (Testudo mauritanica).

The immunocytochemical and histochemical characters of the corticotroph cells of the Turtle adenohypophysis have been studied. These cells are localised in the rostral part of the gland and are revealed by Is anti ACTH (1-24) and (17-39). They are also colored with lead hematoxyline and PAS-Orange G. The corticotroph nature of these cells is confirmed by the study of their modifications after treatment with amphenone and ACTH. The Is anti ACTH also reveal most of the cells of the pars intermedia; while the Is anti beta-MSH reveals only these cells and some scatter cells of the pars distalis.

Adrenocorticotropic Hormone↗
PubMed1975

Diffusion of horseradish peroxidase perfused through the lateral ventricle of the chick telencephalon.

Horseradish peroxidase, perfused into the lateral ventricle of chick brain, freely and slowly diffuses through the cerebral extracellular spaces. The layer of astrocytic end-feet surrounding blood capillaries does not consitute a barrier to the tracer which permeates the basal lamina, diffuses between the pericytic cells and finally accumulates in the intercellular space beneath the tight junctions between contiguous endothelial cells. No evidence was found for transport by micropinocytotic vesicles from the cerebral parenchyma to the capillary lumen.

Animals↗
PubMed1975

[Oxygen toxicity for pulmonary parenchyma. Ultrastructural study by electron microscopy. Physiopathologic data].

The lungs of rats submitted to 24, 36, 48 and 72 hours of pure normobaric oxygen were examined by means of the scanning microscope. The images obtained give a dynamic aspect of the changes in the lesions with two distinct phases: a phase of reactivity at 48 hours, marked by the development of hyperactivity of the granular pneumocytes, a phase of destruction characterised by considerable changes in the alveolar epithelium and filling in of the alveolar lumen with various debris. From these morphological findings, different physio-pathological factors are discussed: the role of the increase in PaO2, the protection provided by the increase in the gradient (A - a) DO2, cerebral and adrenal medullary involvement especially in hypoxemic subjects.

Animals↗