L'ultrastructure des plaquettes sanguines Mise en évidence du glycogène

Résumé L'ultrastructure des plaquettes a été étudiée à l'aide de différentes techniques de fixation, d'inclusion et de coloration.L'association de la fixation au permanganate de potassium, à l'inclusion à l' Araldite et à la coloration à l'acétate d'uranyl s'est montrée très utile pour l'étude de ces éléments du sang.Avec cette méthode nous avons mis en évidence le glycogène des plaquettes. Cette substance se présente sous l'aspect de grains de 180 à 200 Å, très denses, très abondants, dispersés ou formant des agrégats de plusieurs centaines de grains dans la substance fondamentale.Selon les observations réalisées, la membrane des plaquettes est identique aux membranes cellulaires. Nous n'avons reconnu á l'aide des différentes techniques employées, aucune couche que l'on puisse identifier á l'atmosphère plasmatique périplaquettaire de Roskam. Nous avons admis que certains phénomènes dont l'explication reposait sur l'existence de cette atmosphére peuvent être expliqués par la capacité phagocytaire des plaquettes.Dans le granulomére des plaquettes de sang humain normal nous avons observé des granules en baguette de tambour que nous admettons pouvoir être des constituants normaux des plaquettes.Boursier du Centre d'Études d'Histologie et Embryologie Celestino da Costa de l'Institut de Haute Culture.     

Régulation des fonctions de l’épithélium épididymaire des mammifères: état des lieux

Male gametes formed in the testis, the site of spermatogenesis, continue their maturation outside of the gonad in the genital tract. The epididymis is at the centre of this process of post-testicular maturation of spermatozoa, responsible for acquisition of their mobility and their ability to recognize and penetrate an oocyte, essential events for fertilization. During their transit in the epididymal ducts, gametes evolve in a perpetually changing luminal environment due to complex interactions of secretion and reabsorption activities of the epididymal epithelium. These numerous secretion and reabsorption activities are closely regulated in space and time, which makes this epididymal epithelium a very complex tissue subject to an elaborate network of cross-regulations. Apart from classical endocrine and paracrine regulations, the proximal part of the epididymis is also subject to lumicrine regulation by testicular factors which increase the complexity of the regulation networks involved. The present study tries to present an exhaustive review of the factors demonstrated in the literature to exert a modulation of epididymal activity.     

Contribution à la connaisance des Rotifères et des Cladocères de la Région parisienne

Sans résuméStagiaire de Recherches au Centre de Recherches Hydrobiologiques du C.N.R.S.     

Recherches sur les Rotifères des eaux saumâtres VIII. Quelques Rotifères des Marismas espagnoles

Sans résumé     

L'ultrastructure du foie humain lors d'ictères idiopathiques chroniques

Summary Ultrastructural examination of the liver in a case of Rotor's syndrome reveals the presence of unidentified pigment in the hepatocytes and fibrillary degeneration of approximately half of the observed mitochondria.

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Travail subventionné par le Fonds National Suisse de la Recherche Scientifique et par la fondation Fritz-Hoffmann-La Roche-Stiftung zur Förderung wissenschaftlicher Arbeitsgemeinschaften in der Schweiz.     

Le contrôle automatique du flux lumineux dans l'oeil composé des Diptères

In the compound eye of the fly Musca, tiny pigment granules move within the cytoplasm of receptor cells Nos. 1–6 and cluster along the wall of the rhabdomeres under light adaptation, thus attenuating the light flux to which the visual pigment is exposed (Kirschfeld and Franceschini, 1969). Two recently developed optical methods (the neutralization of the cornea and the deep pseudopupil) combined with antidromic and orthodromic illumination of the eye (Fig. 1) make it possible to analyse the properties of the mechanism at the level of the single cell, in live and intact insects (Drosophila and Musca). The mechanism is shown to be an efficient attenuator in the spectral range (blue-green) where cells Nos. 1–6 have been reported to be maximally sensitive (Figs. 4c and d, 5b and 11b). In spite of the fact that the granules do not penetrate into the rhabdomere, the attenuation spectrum they bring about closely matches the absorption spectrum of the substance of which they are composed (ommochrome pigment, dotted curve in Fig. 11b). The dramatic increase in reflectance of the receptors after light adaptation (Figs. 3, 4b, 5a and 11a) can be explained as a mere by-product of the high absorption index of the ommochrome pigment, especially if one takes into account the phenomenon of anomalous dispersion (Chapter 8). The vivid green or yellow colour of the rhabdomeres would thus have a physical origin comparable to a metallic glint. Contrasting with the lens eye in which the pupillary mechanism is a common attenuator for both receptor types (rods and cones), the compound eye of higher Diptera is equiped with two types of pupils adapted respectively to both visual subsystems. A scotopic pupil is present in each of the six cells (Nos. 1–6) whose signals are gathered in a common cartridge of the first optic ganglion. This pupil comes into play at a moderate luminance (0,3 cd/m² in Drosophila; 3 to 10 cd/m² in Musca. Figs 13, 14, 15, 16). A photopic pupil is present in the central cell No. 7 whose signal reaches one column of the second optic ganglion. Attenuating the light flux for both central cells 7 and 8, the photopic pupil has its threshold about two decades higher than the scotopic pupil, just at the point where the latter reaches saturation (Fig. 3b, e-State II of Figs. 6b and 15). The photopic pupil itself saturates at a luminance one to two decades higher still (Fig. 3c, f=State III of Figs. 6c and 15). The two-decades-shift in threshold of these pupil-mechanisms supports the view that receptors 1–6 are a scotopic subsystem, receptors 7 and 8 a photopic subsystem of the dipteran eye. The luminance-threshold of the scotopic pupil (as determined with the apparatus described in Fig. 2) appears to be located at least 3.5 decades (Drosophila) or even 5 decades (Musca) higher than the absolute threshold of movement perception (Fig. 16). After a long period (1 hr) of darkness a light step of high intensity can close the scotopic pupil within about 10 sec (time constant 2 sec as in Fig. 9) and the photopic pupil within no less than 30–60 sec. Some mutants of Drosophila possess only a scotopic pupil (w , Figs. 4 and 5) whereas ommochrome deficient mutants lack both types of pupil (v, cn, see Fig. 7c, d). Comparable reflectance changes, accomplished within about 60 sec of light adaptation, are described for two insects having fused rhabdomes: the bee and the locust (Fig. 17).     

Recherches hydrobiologiques dans les rivières du Congo oriental

Sans résumé     

Structure et fonctionnement des écosystèmes du Haut-Rhône français

Many abandoned stream channels are provided alternatively by river water or groundwater from the interstitial flow. The cyclopoid populations from an abandoned channel of the Rhône river are compared with those from a neighbouring interstitial station. Among the 18 species of cyclopoids found during the present study, only 4 are common to both stations. During 3 years of sampling, the populations living in interstitial waters were rather stable, while the epigean populations were more fluctuating. The latter seem to be influenced by the origin of the water.     

Essai d'une analyse causale du comportement agressif des ouvrières d'abeilles (Apis mellifica)

Sans résuméManuscrit remis en 1953.     

Quelques aspects de l'étude électrophysiologique des réceppteurs sensoiriels des antennes d'Hyménoptères

Insectes Sociaux - With a classical system of amplification and registration, we have obtained electrical responses to variaous stimuli in isolated antennae of Wasps and Bees. A very light...     

Premières observations sur les sphaignes des Alpes-de-Haute-Provence

Sphagnum mosses have been observed for the first time in the Alpes-de-Haute-Provence French department. The four species discovered are confined to Annot sandstone siliceous bedrock formations scattered amongst dominating calcareous bedrock in the area. Both Sphagnum nemoreum and Sphagnum teres are quite frequent in the French Alps while Sphagnum flexuosum and Sphagnum angustifolium on the contrary are rare peat mosses in this chain. Local edaphic and climatic conditions might be responsible for the reduced number of sites discovered. All Sphagnum sites are briefly described. One of them a true peatland is of particular interest and deserves protection.