Étude de l'effet de la température sur la division des cellules séparées de feuilles deCalystegia sepium (L.) R.Br.

Cells mechanically isolated from homogenized leaves ofC. sepium dividein vitro. The rate of cell division is strongly influenced by temperature with the optimum between 31 and 34 °C. The rate of cell division increases proportionally with a rise in temperature up to 31 °C and is accompanied by a reduction in the length of the preparatory phase of the division. A supraoptimal temperature (40 °C) inhibits or stops the cell division which can be restored provided that the cells are transferred to 31 °C. If the preparatory phase to the commencement of cell division is accomplished at 17 °C the cells then exposed to 31 °C divide more rapidly than if they are exposed directly to 31 °C.     

Essai de remplacement de la réfrigération vernalisante par des applications d’acide gibbérellique chez la jusquiame noire bisannuelle (hyoscyamus niger L.)

Applications of various amounts of GA₃ onto the shoot apex of biennial rosette-plantHyoscyamus niger L., exposed to long days and non vernalized, caused internodes formation and stem elongation. The stem length was proportional to the amount of GA₃ applied. Number and length of developed internodes and the whole length of the shoot were maximal in plants treated with a greater amount of GA₃. In the end, stem elongation stopped and plants formed perchedrosettes without flowering. Hence, gibberellic acid participates in mechanisms of flowering only by indirect effect on stem elongation and not directly on flower formation itself.     

Ultrastructure,innervation et fonction de l'épiphyse de l'orvet (Anguis fragilis L.)

Summary The pineal organ of Anguis fragilis contains two essential cell types: pinealocytes and interstitial cells. The scarce outer segments are of different appearance; they show cyclic degenerative changes. Only one intraepithelial ganglion cell has been identified in the material of this study. Although an intracommissural pineal nerve is present, the absence of synaptic junctions of pinealocytes with ganglion cells indicates a loss of photosensory function. Three kinds of vesicles (also dense-core vesicles) originating from Golgi complex are described in the pinealocytes. These secretory vesicles show a vascular polarity. The pinealocyte processes extend to the basement membrane. Secretory material is released into the peripineal space. Efferent sympathetic nerve fibers are described near the pineal epithelium. The nerve endings of these fibers contain three types of vesicles. It is suggested that the pineal organ of Anguis fragilis has a well established secretory function.

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Zusammenfassung Die Epiphysis cerebri von Anguis fragilis enthält zwei wesentliche Zelltypen: Pinealocyten und Zwischenzellen. Die Außenglieder, die nur selten vorkommen, sind verschiedenartig gestaltet und erleiden einen zyklischen Degenerationsprozeß. Im Pinealepithel ließ sich nur eine einzige Ganglienzelle mit Sicherheit nachweisen. Obwohl eine intracommissurale Nervenbahn vorhanden ist, spricht das Fehlen von Synapsen zwischen Pinealocyten und Ganglienzellen für einen Schwund der Lichtsinnesfunktion. In den Pinealocyten werden drei aus dem Golgiapparat stammende Bläschenarten, darunter auch solche mit einem elektronendichtem Inhalt (Granula), beschrieben. Diese Sekretbläschen sind polar auf die Blutgefäße ausgerichtet. Fortsätze der Pinealocyten stehen mit der Basallamina in Verbindung; allem Anschein nach werden hier Substanzen in den periepiphysären Raum abgegeben. Efferente sympathische Nervenfasern sind in der Nähe des Epiphysenepithels zu beobachten. Die Endigungen dieser Fasern enthalten drei verschiedene Bläschentypen. Die Epiphyse der Blindschleiche scheint eine sekretorische Funktion zu haben.

     

Contribution à l’étude de làabsorption du saccharose par des tissus de tubercule de pomme de terre adulte (Solatium tuberosum L.) modalités et influence des phytohormones

Sugar uptake by potato tuber discs was studied. Discs were used “fresh” or after a 24-h ageing period. It was shown that ageing increases (by 3 to 4 times) the rate of glucose and sucrose uptake. Sucrose uptake by fresh tissues was insensitive to the presence of glucose or fructose while a competitive effect was observed after ageing. This indicates the development of an invertase activity, which was inhibited by tris-buffer. Sucrose and glucose uptake by aged discs was dependent on cellular metabolism as shown by the sensitivity to low temperature and metabolic inhibitors (NaCN, DNP, CCCP). Involvement of thiol groups was demonstrated by the inhibition with NEM and PCMBS. Orthovanadate, which decreases phosphate uptake by 85 % (Poderet al. 1986) did not produce any effect on glucose and sucrose uptake by aged tissues. Fusicoccin produced only a slight stimulation (15 %). These results argue in favour of the involvement of specific ATPases in ion and sugar uptake. No involvement of a redox system was observed. ABA and BAP inhibited the uptake induced by ageing but had no effect on the endogenous sugar content. BAP would act by its effect on the amount of ATP while ABA would act at the membrane level. The results are discussed in relation to the mechanisms of transfer of glucosyl groups and to the transport of sucrose by the symplasmic pathway. Reçule     

Ultrastructure de l'épithélium tégumentaire de Glossiphonia complanata (L.) (Hirudinée): cellules épithéliales et organes sensoriels de Bayer

Résumé Le tégument de Glossiphonia complanata comprend, outre les cellules épithéliales banales, de nombreux organes particuliers ou organes de Bayer, regroupés essentiellement sur la face dorsale de l'animal. Ils sont formés par une cellule apicale saillante enchassée dans une cellule musculaire en anneau.L'ensemble de ces formations est étudié du point de vue ultrastructural. Des cellules épithéliales partent des fibres nerveuses afférentes, sans doute vecteur des perceptions de stimuli mécaniques de pression au niveau du tégument; la réponse se faisant sans doute par la contraction de la cellule basale de chaque organe de Bayer, innervée par des fibres nerveuses efférentes, entrainant la saillie de la cellule apicale. Le hérissement de ces nombreuses papilles du tégument dorsal pourrait être un signal perçu par le partenaire sexuel, chez cette Hirudinée à fécondation hypodermique.

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Ultrastructure of the integumentary epithelium of Glossiphonia complanata (L.) (hirudinea): Epithelial cells and sensory organs of bayer

Summary The integument of Glossiphonia complanata, built up by epithelial cells, contains numerous particular organs (Bayer organs), mainly on the dorsal side of the animal. They consist of a protuberant apical cell, which is surrounded by a ring-shaped muscle cell. All the integumentary formations are studied from an ultrastructural point of view. From the epithelial cells issue afferent nerve fibres, considered as vectors of the perception of mechanical stimuli of pressure at the level of the integument; the response no doubt operating by the contraction of the basal muscle cell of each Bayer organ, innervated by efferent nerve fibres, bringing forth the protrusion of the apical cell. The erection of these numerous papillae of the dorsal integument might be a signal perceived by the sexual partner, fecundation occurring in this group of leeches under the integument.

     

L’élastographie par ultrasons ou résonance magnétique : de nouveaux outils de diagnostic en cancérologie

Despite recent progress, breast cancer remains today a major public health problem as it represents the main morbidity incidence for woman with 42,000 new cases and 11,600 deaths per year in France. X-Ray mammography which is the “gold standard” exam for breast screening relies on an excellent sensitivity (nevertheless its quality is varying with respect to breast density). However, its specificity for malignancy diagnosis remains moderate leading to many useless interventions for lesions proven a posteriori to be benign by histology. The other imaging techniques such as echography and magnetic resonance imaging (MRI) also possess their own limits. Echography is strongly operator-dependent. Dynamic MRI with injection of contrast agents has a high sensitivity for breast cancer detection (>90%) but suffers from a moderate specificity (50 to 80% according to the type of cancer). In parallel, although it is strongly subjective, the act of palpation remains today a major act in the workflow of breast screening. Since Egyptian ancient ages, the physicians practise the act of palpating body parts in order to determine tissues stiffness and a hardly deformed mass within an organ is often related to the presence of an abnormal lesion. Palpation is not only useful for screening and diagnosis as the surgeon also uses it during interventions to be effectively guided towards the pathological area. Recently, new techniques based on ultrasound or magnetic resonance imaging finally made it possible to map organs elasticity in a quantitative way. These “elastography” techniques could play soon an important role in medical imaging.     

Excrétion de phosphatase acide par les cellules mucipares de la branchie de Mytilus edulis L.

Résumé Dans toutes les cellules mucipares de la branchie de Mytilus edulis L., quelques grains de secretion montrent une activité phosphatasique acide, décelée par la méthode cytochimique de Gomori appliquée au microscope électronique. A la proximité de ces grains se trouvent des dictyosomes golgiens où une activité phosphatasique se décèle dans les parties latérales des cisternes et dans les vésicules qui en émanent. Au moment de l'excrétion, tous les grains de sécrétion confluent et la phosphatase acide active est incluse dans l'amas de mucus expulsé dans la cavité palléale. Le rôle digestif de ces amas — et non purement mécanique — peut ainsi être considéré comme hautement probable. De telles manifestations enzymatiques sont totalement absentes dans le tapis muqueux ainsi que dans les cellules qui le constituent.

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Excretion of acidic phosphatase by the goblet-cells of the gill of Mytilus edulis L.An electron microscopic study

Summary Acidic phosphatase activity detected by the Gomori method applied to E.M., has been found in a few secretion granules of each goblet cell of the gill of Mytilus edulis L. In the close proximity of those granules golgian dictyosomes always occur, with acidic phosphatase activity in the lateral parts of the cisternae and in the vesicles arising from the latter. When the mucus is extruded, active and non active secretion granules are mixed and thus, acidic phosphatase activity is regularly found in the mucous tufts extruded into the palleal cavity. Therefore the digestive role — and not merely mechanic — of the mucous tufts may be considered as highly probable. Conversely, the secretion granules from which arises the continuous mucous cover of the epithelium and this cover also, are entirely devoid of any acidic phosphatase activity.

     

Sexualisation de la gonade deViviparus viviparus L. (mollusque gastéropode prosobranche à sexes séparés)

Résumé La sexualisation de la gonade chezViviparus viviparus se manifeste d'abord au niveau morphologique: tandis que l'ovaire s'organise en un tubule très peu ramifié, à large lumière, le testicule compact bourgeonne de nombreuses excroissances. Dans l'ovaire les cellules non germinales, futures cellules folliculeuses, se mettent en place autour des cellules germinales et les processus de la préméiose débutent précocement. Au contraire plusieurs étapes se succèdent au cours de la morphogenèse de la gonade mâle: après une phase d'intense multiplication cellulaire, accompagnée de la ramification du testicule, la lumière se creuse par dégénérescence des cellules centrales. Contre la lame basale, les cellules non germinales évoluent en cellules nourricières tandis que se différencient les spermatogonies primaires. La différenciation des premiers gamètes mâles est tardive.     

Induction de préséances entre bourgeons cotylédonaires par des stimulations mécaniques chezBidens pilosus L.

Pricking one of the cotyledons of aBidens pilosus L. (var.radiatus) seedling decapitated just above the cotyledons four times in succession induces after one minute the dominance of buds on the unaffected side.     

L’avenir de l’oncologie passe-t-il par la médecine nucléaire ?

During the last decennials, nuclear medicine demonstrated a lot of significant progresses, so that “nuclear oncology” could be considered now as a well recognized entity. These progresses have been made on one hand in the diagnostic field, and on the other hand for therapeutic applications of radiopharmaceuticals able to target tumour cells, the number and performances of which being continuously growing. For diagnosis, beyond its capability to visualize tumour lesions otherwise difficult to demonstrate, it could be said that nuclear medicine is useful for the tumour characterization, allowing imaging of prognosis factors and criteria of treatment's choice, and evaluation of treatments efficiency as well. In the therapeutic field, while thyroid carcinomas treatment using iodine 131 is still of interest and benefits of recent improvements, internal targeted radiotherapy is clearly becoming clinically useful, as it has been proved that it could improve patients’ survival in combination with other treatments. That is true for radio-immunotherapy of follicular lymphoma and bone metastasis treatment, and probably in the very near future for several solid tumours. This paper reviews the most significant aspects of these recent progresses, in order to convince that nuclear oncology has become a full part of oncology.