Matches in SemOpenAlex for { <https://semopenalex.org/work/W2015686690> ?p ?o ?g. }
- W2015686690 endingPage "185" @default.
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- W2015686690 abstract "Les transformations du chondriome pendant la spermatogénèse ont été étudiées à l'aide du microscope électronique chez une cinquantaine d'espèces animales zoologiquement très variées. Elles sont décrites en détail pour trois d'entre elles: Rat, Testacella (Mollusca, Gastropoda), Pieris (Insecta, Lepidoptera). Chez ces espèces le chondriome, d'ultrastructure habituelle au départ (spermatogonies), se multiplie abondamment et subit des modifications qui lèguent au spermatozoïde des corps mitochondriaux d'ultrastructure inhabituelle. Les faits les plus saillants de cette évolution sont: Chez le Rat: (1) l'apparition d'une substance nouvelle, claire, nommée pseudomatrice, dilatant les espaces intermembranaires des crêtes (espaces intracristaux); (2) l'augmentation d'opacité des espaces matriciels, avec une réduction concomitante de leur volume qui amène une inversion des contrastes par rapport à l'ultrastructure normale; (3) l'expulsion de la pseudomatrice; (4) l'allongement et l'enroulement autour du flagelle de ces mitochondries modifiées, qui finalement s'alignent les unes derrière les autres, tout en conservant leur individualité, en deux hélices, jointives et de pas constant, entre lesquelles s'intercalent localement une troisième, et parfois une quatrième hélices; Chez la Testacelle: (1) l'apparition d'une pseudomatrice, accompagnée d'une réduction et d'une opacification des espaces matriciels, comme chez le Rat; (2) la disposition en sphères emboîtées des lames matricielles; (3) le groupement périflagellaire de ces mitochondries à structure concentrique; (4) leur fusion en un seul chondriosome, de dimensions gigantesques; (5) l'évanouissement des structures de l'internum mitochondrial, véritable métamorphose au cours de laquelle membranes, matrice, pseudomatrice et granules disparaissent, tandis qu'apparaissent des domaines ordonnés; (6) la croissance des domaines ordonnés, qui s'organisent finalement en deux manchons concentriques dont la structure, paracristalline, a été analysée, et dont la nature, non établie avec certitude, est supposée protéique; il est suggéré que les éléments constitutifs du réseau paracristallin, petits bâtonnets creux de 90 Å. représentent un état particulier des protéines respiratoires; (7) la démixtion de substances, supposées lipidiques en majorité, d'ultrastructure variée, qui forment trois hélices distinctes (dont deux sont jumelles) logées entre les deux manchons paracristallins; cités sont erronés, douteux ou insuffisamment prouvés. (4) Cette augmentation du chondriome est favorable à la recherche des modalités de la multiplication mitochondriale; les constatations faites sur le Rat conduisent à émettre l'hypothèse que de nouvelles mitochondries se forment par induction au voisinage immédiat d'une mitochondrie préexistante, ou par croissance et scission d'une mitochondrie-mère; elles forment alors des groupements particuliers de mitochondries qui terminent leur maturation, puis se dispersent dans le cytoplasme. Dans les deux cas, la présence d'une mitochondrie initiale serait nécessaire. Cytochimie et biochimie. Les colorations classiques après fixation, la coloration supravitale au vert Janus B et la détection de l'activité succino-déshydrogénasique à l'aide du tétrazolium nitro-bleu, mises en parallèle avec les images de la microscopie électronique, concordent à montrer que, à la fin de la spermatogénèse, les enzymes respiratoires membranaires sont non seulement présentes, mais concentrées, même dans les cas où la morphologie est profondément aberrante. Les implications physiologiques de cette concentration enzymatique sont discutées. The transformations of the chondriosomes during spermatogenesis have been studied with the electron microscope in nearly 50 widely varied species. They have been described in detail for three of them: Rat, Testacella (Mollusca, Gastropoda), Pieris (Insecta, Lepidoptera). In these species, mitochondria exhibiting normal ultrastructure at the beginning of spermatogenesis (spermatogonia) increase greatly in number and volume, and undergo progressive modifications which finally provide the spermatozoon with mitochondrial derivatives of unusual ultrastructure. The more prominent features of this evolution are:oI.In the Rat: (1) the appearance of a new, clear substance, named pseudomatrix, which dilates the intermembranous spaces of the cristae (intracristal spaces); (2) an increase in opacity of the matricial spaces, with a concomitant decrease of their volume, which produces a reversal of contrast with respect to normal ultrastructure; (3) an expulsion of the pseudomatrix; (4) a lengthening and coiling around the flagellum of these modified mitochondria which, finally, line up one behind the other and, although keeping their individuality, give rise to two contiguous, uniformly pitched helices between which a third and sometimes a fourth helix is intercalated;II.In Testacella: (1) the appearance of pseudomatrix accompanied by a reduction in volume and increase in density of the matricial spaces, just as in the Rat; (2) the arrangement of the lamellae of condensed matrix in concentric spheres; the periflagellar clustering of these concentrically structured mitochondria; (4) their fusion into a single chondriosome of huge dimensions; (5) the disappearance of the mitochondrial internal structure, a true metamorphosis during which membranes, matrix, pseudomatrix, and dense granules disappear, while orderly domains appear; (6) the expansion of the orderly domains, which finally form two concentric muffs of paracrystalline structure, the nature of which has not been completely ascertained but is believed to be proteinic; the constitutive elements of the paracrystalline network are hollow rodlets measuring 90in diameter, and it is suggested that they represent a particular state of the respiratory proteins; (7) the demixing of ultrastructuraly varied substances, believed to be primarily lipidic, which form three distinct helices (two of them being twins) lodged between the two paracrystalline muffs;III.In Pieris: (1) a dilatation of the mitochondria with a clarification of the matrix and without the appearance of any pseudomatrix, unlike the two previous cases; tion; the observations made on the Rat lead us to suggest that new mitochondria are formed by induction in the close proximity of a preexisting mitochondrion, or by growth and division of a parent mitochondria; then, they form typical clusters of mitochondria which mature and disperse throughout the cytoplasm. In both cases, the initial presence of mitochondria would be necessary.III.Cytochemistry and Biochemistry. Classical staining after fixation, supra-vital staining with Janus-Green B, and succino-dehydrogenase activity detection with nitro-BT compared with electron microscopic images, concur to show that, at the end of spermatogenesis, the respiratory enzymes of the membranes are not only present, but exist in a concentrated form, even in the cases in which the morphology is greatly aberrant. The physiological implications of this high enzyme concentration are discussed. In the Rat: (1) the appearance of a new, clear substance, named pseudomatrix, which dilates the intermembranous spaces of the cristae (intracristal spaces); (2) an increase in opacity of the matricial spaces, with a concomitant decrease of their volume, which produces a reversal of contrast with respect to normal ultrastructure; (3) an expulsion of the pseudomatrix; (4) a lengthening and coiling around the flagellum of these modified mitochondria which, finally, line up one behind the other and, although keeping their individuality, give rise to two contiguous, uniformly pitched helices between which a third and sometimes a fourth helix is intercalated; In Testacella: (1) the appearance of pseudomatrix accompanied by a reduction in volume and increase in density of the matricial spaces, just as in the Rat; (2) the arrangement of the lamellae of condensed matrix in concentric spheres; the periflagellar clustering of these concentrically structured mitochondria; (4) their fusion into a single chondriosome of huge dimensions; (5) the disappearance of the mitochondrial internal structure, a true metamorphosis during which membranes, matrix, pseudomatrix, and dense granules disappear, while orderly domains appear; (6) the expansion of the orderly domains, which finally form two concentric muffs of paracrystalline structure, the nature of which has not been completely ascertained but is believed to be proteinic; the constitutive elements of the paracrystalline network are hollow rodlets measuring 90in diameter, and it is suggested that they represent a particular state of the respiratory proteins; (7) the demixing of ultrastructuraly varied substances, believed to be primarily lipidic, which form three distinct helices (two of them being twins) lodged between the two paracrystalline muffs; In Pieris: (1) a dilatation of the mitochondria with a clarification of the matrix and without the appearance of any pseudomatrix, unlike the two previous cases; tion; the observations made on the Rat lead us to suggest that new mitochondria are formed by induction in the close proximity of a preexisting mitochondrion, or by growth and division of a parent mitochondria; then, they form typical clusters of mitochondria which mature and disperse throughout the cytoplasm. In both cases, the initial presence of mitochondria would be necessary. Cytochemistry and Biochemistry. Classical staining after fixation, supra-vital staining with Janus-Green B, and succino-dehydrogenase activity detection with nitro-BT compared with electron microscopic images, concur to show that, at the end of spermatogenesis, the respiratory enzymes of the membranes are not only present, but exist in a concentrated form, even in the cases in which the morphology is greatly aberrant. The physiological implications of this high enzyme concentration are discussed." @default.
- W2015686690 created "2016-06-24" @default.
- W2015686690 creator A5023667683 @default.
- W2015686690 date "1962-05-01" @default.
- W2015686690 modified "2023-09-24" @default.
- W2015686690 title "Contribution à la connaissance du chondriome" @default.
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