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Biomedical subjects

G Grignon

Publications and source records attributed to G Grignon.

At least 55 records · Page 3Linked to original sources
PubMed1987

Ultrastructural study of epithelial cells and basement membrane. Differentiation of the rat epididymis after prenatal irradiation.

The effects of prenatal irradiation on the testis are well documented, but less is known about its effects on epididymal differentiation. Pregnant rats were irradiated on the 18th day of gestation. The increase in microfilaments and lipid inclusions in the epithelial cells, in favor of a direct radiation effect, is maximal at birth and disappears thereafter. Narrow cells and clear cells show a normal differentiation pattern. On the other hand, the principal cell maturation is largely altered. The synthesis capacities are decreased based on a reduction in the size of the Golgi apparatus and the smooth endoplasmic reticulum. The aspects of invaginations of the apical plasmalemma, coated vesicles and multivesicular bodies are not modified, suggesting normal absorption functions. The epithelial basement membranes become irregular and thicker than normal, enfolding the basal part of the epithelial cells. The basement membrane proteoglycans, demonstrated by the cationic marker polyethyleneimine, are irregularly distributed in contrast to the normal pattern. These modifications of the principal cells and the basement membrane are more prominent in the proximal epididymis. This suggests a differential maturation dependence of the epithelial cells on the luminal factors, normally secreted by the testis, and likely disturbed by prenatal irradiation which leads to germ cell degeneration, and then to a new balance in the seminiferous epithelium.

Animals↗
PubMed1987

Influence of testicular secretions on differentiation in the rat epididymis: ultrastructural studies after castration, efferent duct ligation and cryptorchidism.

The differentiation of the rat epididymis was studied in prepubertal castrated, ligated or cryptorchid rats, in order to assess the influences of blood-borne and luminal androgens. The principal cells showed partial differentiation: decrease in cell height, decreased numbers of cytoplasmic organelles implicated in the elaboration phenomena (Golgi apparatus, smooth endoplasmic reticulum), whereas the organelles implicated in the absorptive function remained relatively intact. The lamina densa of the basement membrane underlying the epithelium was irregular, thicker than normal and followed the irregular outline of the basal parts of the epithelial cells. These changes were evident in castrated rats, to a lesser degree in ligated and cryptorchid rats, and were more prominent in the initial part of the duct. On the other hand, the narrow cells and the clear cells followed a normal differentiation pattern in the experimental rats, suggesting that a differential androgen dependence exists among the various type of epididymal cells.

Androgens↗
PubMed1987

[Ultrastructural analysis of anionic sites of the basal membrane of the seminiferous tubules of subjects with severe oligospermia].

Several morphological alterations of the basement membrane of the seminiferous tubules have been reported in the patients presenting with a testicular sterility. The proteoglycans are one of the major components of the basal membrane and may be ultrastructurally defined by the use of the cationic marker polyethyleneimine (PEI). In comparaison to the normal distribution of the anionic sites labelled by PEI which is characterized by a regular pattern of distribution along both the epithelial and the interstitial faces of the lamina densa, the pattern of distribution of the sites is largely altered in 6 patients, 27 to 40 years of age, with oligo- or azoospermia. Several types of alterations are reported: parallel thickening of the lamina densa with an abnormal distribution of the anionic sites inside the lamina densa, stratifications of the basal membrane depressing the seminiferous epithelium with anionic sites labelled on both faces of the lamina densa-like layers, massive expansions of the lamina densa with either a regularly circumferential labelling of the sites or a random type of distribution. The digestion of the sites by the enzyme heparitinase is highly suggestive of the presence of proteo-heparan-sulfate. The analysis of the distribution of the anionic sites may represent a usefull tool for studying the pathogenesis of testicular sterility.

Adult↗
PubMed1987

[The articular cartilage of the patella in scanning electron microscopy].

The authors have studied 50 samples of patellar cartilage, normal and pathological, obtained by biopsy, using a scanning electron-microscope. The normal cartilage shows characteristic regular wave-like undulations. The size of these waves varied between 5,000 and 7,000 nm and the undulations were linked by regularly-spaced fibrillary bridges. In a case with an osteochondral fracture, the fracture site was covered by peripheral cartilage, as had previously been shown by Ghadially. Eighteen cases of patellar chondropathy were divisible into three groups: group I (four cases) showed fibrillary chondropathy, of cerebriform appearance and without fibres. Group II (12 cases) showed a fibrillary chondropathy with loss of geometrical regularity and a staghorn appearance. Group III (two cases) showed an oedematous chondropathy with destruction of fibres. In group II, the presence of bundles of fibres with microfractures indicates a potential for progress to frank arthrosis.

Adolescent↗
PubMed1987

[Postnatal development of zinc levels in the epididymis and testis in rats under normal and experimental conditions].

Postnatal testicular and epididymal zinc concentration in the rat was investigated by means of differential pulse polarography. The zinc concentration increased gradually from birth to day 90 in the testis and up to day 60-90 in the epididymis with an abrupt increase on day 21. No marked variation in the zinc content was observed all along the epididymal duct. Experimental castration and efferent duct ligation were carried out in order to assess the influence of blood-borne and luminal androgens on epididymal zinc content. In prepubertal rats, unilateral castration and efferent duct ligation did not affect the zinc content of the epididymis. Moreover, zinc concentration was not affected by bilateral castration which induced very low plasma testosterone levels. These results suggested that epididymal zinc content did not depend upon endocrine testicular secretions, especially androgens. On the other hand, in adult rats efferent duct ligation and cryptorchidism resulted in about 50 and 70% reduction, respectively of the testicular and epididymal zinc content. A correlation was found between the absence of testicular fluid and spermatozoa or the alteration of germ cells and the decrease in epididymal and testicular zinc content.

Aging↗
PubMed1986

Purification of androgen-binding protein from rat testis using high-performance liquid chromatography and physicochemical properties of the iodinated molecule.

The androgen-binding protein (ABP) has been purified 87,500-fold from rat testis using 4 steps of HPLC, with a yield of 14%. The molecule was 99% pure with a specific activity estimated to 16,600 pmol/mg protein. The iodinated molecule was eluted in 2 peaks in Sephacryl S300 gel filtration with a molecular mass estimated to be 92,600 +/- 3300 and 50,300 +/- 4000 Da. The column isoelectrofocusing of 125I-ABP demonstrated 3 isoproteins isoelectric at pH 4.7, 4.9 and 5.3 and the sedimentation coefficient was estimated to be 4.7 S in sucrose gradient ultracentrifugation. The 125I-ABP had similar physiochemical properties to the non-labelled ABP of epididymis.

Androgen-Binding Protein↗
PubMed1986

Ultrastructural study of the Sertoli cell and the limiting membrane in the seminiferous tubule of the adult cryptorchid rat.

Cryptorchidism was simulated in 13-15-day-old rats by severing the gubernaculum testis and fixing the testis to the abdominal wall. Ultrastructural examination of the testis was made 100 days after birth when a number of modifications to the seminiferous tubules were noted. Germ cells were scanty, with only occasional spermatogonia and primary spermatocytes persisting. The nuclei of Sertoli cells were regular and oval or indented in shape. Their cytoplasm was characterized by a rich smooth endoplasmic reticulum, lipid inclusions and mitochondria with tubulo-vesicular cristae indicative of steroïdogenic activity. The decrease in the number of the germ cells induced a membrane rearrangement with numerous tight junctions and interdigitations between the Sertoli cells. Sertoli cell-specific junctional complexes were very extensive. The lamina propria of the seminiferous tubule appeared thickened and folded and the multilayered basal lamina had complex folds. After fixation with glutaraldehyde containing lanthanum, the latter substance was identified in the basal intercellular spaces of the seminiferous tubules indicating that the blood-testis barrier remains functional in the intra-abdominal testis.

Animals↗
PubMed1986

Influence of testicular secretions on epididymis oxidative metabolism in the rat.

The oxidative metabolism of the epididymis has been investigated in 40-day-old rats under normal and experimental conditions. No difference in the oxidative metabolism was observed between the initial, middle and terminal segments of the epididymal duct of normal rats. After bilateral or unilateral castration or efferent duct ligation, the oxidative metabolism was found to be exclusively dependent upon plasmatic androgens in the terminal segment in contrast to the proximal segment oxidative metabolism which is dependent of both normal luminal secretions and normal plasmatic androgens.

Animals↗
PubMed1985

Histoimmunological identification of a prolactin-like substance in rodent testis.

Anti-rat prolactin (PRL) antibodies were localized by histoimmunological methods in the cytoplasm of testicular interstitial cells, Sertoli cells, spermatogonia and primary spermatocytes of the rat and mouse. Control of specificity by affinity chromatography methods showed this PRL-like material to be non-specific in these testicular tissues, but specific in adenohypophyseal cells. These results are discussed.

Animals↗
PubMed1985

[Carbonic anhydrase activity in the epididymis of the developing rat].

The enzyme, carbonic anhydrase (CA), has been studied by an histochemical procedure during the postnatal development of the rat epididymis. Its activity first appeared at Day 14 in the early differentiating cells, i.e. the narrow cells, and only in them. These cells, found in the initial segment and the head of the adult epididymis, showed considerable activity. At Day 35 they disappeared in the other segments (corpus and tail), while the light cells which became apparent immediately showed more discrete CA activity. No carbonic anhydrase activity was found in the seminiferous epithelium, the testicular interstitial tissue or the rete testis.

Age Factors↗
PubMed1983

Immunocytochemical localization of angiotensinogen in rat liver and kidney.

The renin substrate, angiotensinogen, was localized by immunocytochemistry in liver and kidney of normal rats by the use of an antiserum directed against pure rat angiotensinogen. This substrate was also examined in rats after bilateral nephrectomy, which is known to increase plasma angiotensinogen, and in rats treated with colchicine, which inhibits serum protein secretion. In normal rat liver, light microscopy showed the presence of immunoreactive material in a very few cells. The number of stained hepatocytes rose in rats treated with colchicine or after bilateral nephrectomy. Immuno-staining increased further when rats were both nephrectomized and colchicine treated. In the kidney, angiotensinogen was specifically located as granular formations in nephrocytes of the proximal tubule but never in the granular cells of the juxtaglomerular apparatus. The localization of these granular formations under the brush border suggests that angiotensinogen is reabsorbed from the glomerular ultrafiltrate rather than synthesized in the kidney.

Angiotensinogen↗
PubMed1982

Ultrastructural study of seminiferous tubules in the rat after prenatal irradiation.

Is the presence of germinal cells necessary for the Sertoli cells to acquire normal features? To respond to this question we have studied the development of the Sertoli cells in rats irradiated at the end of the foetal life. In the prenatal irradiated rats, the lumen of the seminiferous tubules appears later than in the control rats. The Sertoli cells show numerous flexuose apical processes, with central microtubule bundles. These processes regress progressively after the 40th day of life when the tubular lumen appears; numerous junctional complexes differentiate with the same structure as those of control animals. There are important dilatations of the intercellular spaces. The cytoplasmic organelles show a normal development up to the 40th day of life. After this period, the rough endoplasmic reticulum and the Golgi apparatus clearly regress while important dilatations appear in the smooth endoplasmic reticulum and persist in the adult animal. From the 35th day on, the basal lamina of the seminiferous tubules is irregular and multilayered. The differentiation of the Sertoli cells seems to be independent of the presence of germinal cells until the 40th day of life and presents several particularities; thereafter the Sertoli cells show signs of regression.

Animals↗
PubMed1982

[Ultrastructural immunocytochemical localization of hormonal principles of the adenohypophysis in the terrestrial tortoise (Testudo mauritanica Dumer)].

An ultrastructural immunocytochemical study is realized with mammalian adenohypophyseal anti-hormone antibodies and permits characterization of five cellular types in Testudo mauritanica Dumer. The antiproteic-hormone antibodies STH, LTH and ACTH are each fixed on a well individualized cellular type. The anti-glycoproteic hormone antibodies identify a TSH cell; but two cell populations respond to the same beta LH antigonadotropic antibody. The question of the unicity or the duality of the gonadotrope cells is expressed.

Adrenocorticotropic Hormone↗
PubMed1982

[Scanning electron microscopy study of the lung].

The pulmonary parenchyma is characterized by a marked development of blood-tissue and gaz-tissue interfaces. Thus the study of the lung is easy by scanning electron microscopy. Numerous and various technics of sample preparation are described and discussed. They permit to carry out morphological and morphometrical studies of fine structures in the adult and foetal lung surface. The systematisation of the different parts of the pulmonary air tract (bronchi, bronchioli, alveolar ducts and alveoli) is analysed. The different epithelial cells are characterized by their apical differentiations and by their often specific localization. Bronchial (mucus), bronchiolar and alveolar (surfactant) secretions are studied after different fixations. The observation of the vascular network (arteries, veins and pulmonary capillaries) is performed after vascular injection of fixator liquid. The scanning electron microscope is also used to study the alveolar macrophage (in situ or in cell culture), the visceral surface of pleura, the pre and post-natal development of the lung parenchyma. The SEM is a complementary and modern method of lung observation. It gives a dynamic view of the fine structure of lung surfaces, which appears needful for the study of the local histophysiological processes.

Animals↗
PubMed1981

[Preparation of antisera against some sequences of somatostatin synthetized on resin. Application to the immunological detection of somatostatin systems: preliminary results (author's transl)].

Specific SRIF(1-14) fragments were synthetized on resin using conventional procedures. Rabbits received subcutaneously peptidyl resins in complete Freund adjuvant emulsion. The presence of antibodies was assessed by immunocytochemical and radioimmunological assays. 1. Peptidyl resins lead to antibodies production; their specificity depends on sequence and molecular configuration of the peptide on the resin. Anti-resin antibodies were not detected. 2. In the brain, SRIF(1-4) (in rat) and SRIF(10-13) (in garden-dormouse) can be demonstrated in neurophysins--positive cells of both paraventricular and supraoptic nucleus, but never in hypothalamic or extrahypothalamic SRIF(1-14)--positive neurophysin negative cells. 3. Endocrine cells of pancreatic islets contain SRIF(6-9) (in man) or SRIF(10-13) (in rat, mouse, garden-dormouse); generally, these cells are not detected by SRIF(1-14) anti-serum. Moreover, SRIF(10-13) positive cells are also detected by specific glucagon antibodies. However, it cannot be concluded that SRIF(10-13) antibodies reveal the common Thr-Phe-Thr-Ser fragment in the entire glucagon molecule. It is postulated that antibodies to several SRIF tetrapeptides reveal molecular fragments provided by the functional cleavage of an hypothetical prohormone or by the inactivation of SRIF(1-14) molecule in target cells.

Animals↗