La cuticule proctodéale des insectes

Résumé La formation des divers types de cuticule rectale a été suivie au cours de la mue chezKalotermes flavicollis (Isoptera). Dans l'épithélium rectal, l'épicuticule externe est formée de couches alternativement sombres et claires, comme dans les autres types de cuticule; l'épicuticule interne présente d'abord une fine lamellation de sa région superficielle, lamellation qui disparaît ensuite. Sur les papilles rectales, l'épicuticule externe a d'abord le même aspect, mais ensuite des différences apparaissent dans l'évolution des différentes couches; ces différences sont encore plus accentuées dans les dépressions épicuticulaires, où les couches superficielles de l'épicuticule externe disparaissent. Sur le cadre bordant les papilles, le dépôt de l'épicuticule externe est peu différent de ce qu'on observe sur l'épithelium rectal; l'épicuticule interne, très mince, présente là aussi une lamellation temporaire; le reste de la cuticule acquiert d'emblée la structure homogène observée pendant l'intermue. Dans tous les cas, la sécrétion de la cuticule (y compris la sous-cuticule) est terminée au moment de l'exuviation. Les modifications des cellules sont brièvement décrites; les cellules des papilles rectales subissent une dédifférenciation complète de leur surface apicale, mais, sur les faces latérales, les associations des mitochondries avec les replis des membranes plasmiques subsistent en grande partie.

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Proctodeal cuticle of insectsII. Formation during the molt

Summary The formation of the different kinds of rectal cuticle has been followed during the molt inKalotermes flavicollis (Isoptera).In the rectal epithelium, the outer epicuticle consists of alternating dark and light layers, as previously described in other types of cuticle; the inner epicuticle first exhibits in its superficial part a thin multilayered pattern, which later disappears.In the rectal papillae, the outer epicuticle has primarily the same appearance, but the evolution of the various layers is somewhat different; even more pronounced differences occur in the epicuticular depressions where the more superficial layers of the outer epicuticle disappear.In the border of the rectal papillae, the outer epicuticle is laid down according nearly the same way as in the rectal epithelium; the temporary multilayered pattern of the very thin inner epicuticle also may be observed; the underlying part of the cuticle, as soon as it is formed, shows the homogeneous appearance observed during the intermolt.In all the cases, the secretion of the cuticle (sub-cuticle included) is achieved when the ecdysis occurs.The modifications affecting the cells are briefly described; the apical surface of the rectal papillae cells undergoes a complete dedifferentiation, but, on the lateral faces, the associations of mitochondria with plasma membrane interdigitations for a large part remain unchanged.

     

A cinefluorographic study of mandibular movement during feeding in the rat (Rattus norvegicus)

The anatomy of the masticatory apparatus, and particularly of the mandibular joints, has led to the view that mandibular movement in the Rodentia is predominantly propalinal, or forwards and backwards in direction. As part of an investigation into the mechanism of function of the mandibular joints in these animals, the feeding behaviour of "August" strain and "Wistar" rats was examined by cinephotography and cinefluorography. The rats were trained to feed on barium sulphate impregnated biscuit and animal cake and to drink radio-opaque liquids. Cinefluorographic recordings of ingestion, mastication, deglutition and of drinking were taken in both the lateral and dorso-ventral projections.
Analysis of the recordings has shown a fundamental separation of ingestive and masticatory activity in the rat, which can be attributed to the morphology of the jaws and particularly to the disparity in the lengths of the mandibular and maxillary diastemas. To bring the incisor teeth into occlusion for ingestion, the mandible is brought forward through the rest position and the condyle into articulation with the anterior part of the fossa. In mastication the condyle is moved backwards to bring the molar teeth into occlusion and the condyle into articulation with the posterior articular facet on the fossa. Once the mandible has been moved into the appropriate position for either ingestion or mastication and deglutition, the movements involved in the separation or chewing of the food are cyclical with combined horizontal and transverse movements as well as the fundamental vertical movement acting to open and close the mouth. The basic movement of ingestion carries the mandibular incisors upwards and forwards across the lingual surfaces of the maxillary incisors, so separating the bite. The grinding stroke of mastication is a horizontal movement carrying the mandibular molars anteriorly across the maxillary.     

Botanische Beobachtungen im Jahre 1873

Ohne Zusammenfassung     

Testing the efficacy of antimicrobial peptides in the topical treatment of induced osteomyelitis in rats

Joint replacement infections and osteomyelitis are among the most serious complications in orthopaedics and traumatology. The risk factors for these infections are often bacterial resistance to antimicrobials. One of the few solutions available to control bacterial resistance involves antimicrobials, which have a different mechanism of action from traditional antibiotics. Antimicrobial peptides (AMP) appear to be highly promising candidates in the treatment of resistant infections. We have identified several AMP in the venom of various wild bees and designed analogues that show potent antimicrobial activity and low toxicity against eukaryotic cells. The aim of the present study was to test the efficacy of one of those synthetic peptide analogues for the treatment of acute osteomyelitis invoked in laboratory rats. Femoral cavities of 20 laboratory Wistar rats were infected with Staphylococcus aureus. After 1 week, eight rats received an injectable calcium phosphate carrier alone, another eight rats were treated with a calcium phosphate mixed with AMP, and four rats were left without any further treatment. After another week, all rats were euthanized and radiographs were made of both the operated and healthy limbs. The animals with the carrier alone exhibited more severe acute osteomyelitis on radiographs in comparison to the recipients of the calcium phosphate carrier loaded AMP and untreated infected individuals. Based on the results of the above mentioned experiment, it was concluded that when injected directly into the site of femoral acute osteomyelitis, the calcium phosphate carrier mixed with AMP reduced osteomyelitis signs visible on radiographs.