共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
4.
V Dantzer 《Acta anatomica》1984,118(2):96-106
The three-dimensional development of the separated parts of the porcine placenta from 9 Danish Landrace sows at gestational stages from 20 to 100 days was studied. After cautious separation of the allantochorion and the endometrium in a 1 mM buffered ethylenediaminetetraacetic acid solution, the separated parts were processed for scanning electron microscopy by routine methods. The macroscopic enlargement resulted from primary and secondary circular folds or plicae, which were permanent on the maternal side, whereas they were mainly non-permanent on the fetal side. The areolar placenta and interareolar placenta with formation of permanent microscopic folding on both sides were described. The observations of the separated parts yielded new information on the development of surface enlargement during gestation and revealed a hitherto unknown regular architecture of the endometrium by the formation of parallel primary ridges or rugae with secondary ridges or rugae at their sides subdividing the maternal troughs or fossae. This configuration on the maternal side explains the transformation of the regular chorionic ridges from the 63-day stage into bulbous protrusions at the 100-day stage. Based on these observations the precise terminology used above was proposed. 相似文献
5.
Prof. Pietro Motta Peter M. Andrews Felice Caramia Silvia Correr 《Cell and tissue research》1977,176(4):493-504
Summary The pancreatic acinar cell surfaces have been studied by SEM with a dissection technique and correlated with results obtained by TEM. The SEM results demonstrate characteristic arrangement of microplicae which in some areas are densely packed.In many areas, the microplicae are distributed in such a manner that they create zones with typical geometrical shapes and show a relatively smooth surface.These smooth areas may coincide, as indicated by correlated TEM results, with the limits of intimate contact between adjacent acinar cells which, in turn, represent part of the junctional complex. Another aspect revealed by these SEM preparations concerns the presence of groups of densely packed microplicae, arranged in regular rows and distributed along some grooves and/or infoldings of the cellular surface. On the basis of SEM and TEM information, it is likely that these structures correspond to intercellular (and possibly, in some cases, intracellular) canaliculi which topographically form a kind of extensive microlabyrinthine arrangement running along all the cell sides.One final point revealed by fractured samples concerns the finding of spherical zymogen droplets within the vesicles of the Golgi complex. Because in many scanning images these vesicles appear connected by small openings, it is suggested that they may represent a system of intercommunicating chambers (vacuoles) through which the zymogen droplets can be continuously accumulated and discharged into the acinar lumen. 相似文献
6.
Schistosoma haematobium miracidia were collected from a locality with a high prevalence of human infection with the animal parasite, S. mattheei, which hybridizes with S. haematobium, and from 2 localities with negligible infection rates. The terebratoria of the miracidia from these localities were compared with each other, with laboratory maintained S. haematobium and with four populations of S. mattheei by means of scanning electron microscopy. It was found that the terebratorial membrane of certain of the S. haematobium miracidia from the locality with a high S. mattheei prevalence in humans, resembled the more intricate membrane of S. mattheei. This suggests introgressive hybridization between S. haematobium and S. haematobium x S. mattheei. 相似文献
7.
Changes in the appearance of the vaginal epithelium of rats during the estrous cycle were seen by scanning electron microscopy. Bacterial colonization of this tissue appeared to be influenced by these changes. 相似文献
8.
Substitution of galactose, xylose, or mannose for glucose in the growth medium of L cells or the addition of equal concentrations of the alternate sugars to glucose-containing medium results in marked morphologic changes. The changes are revealed by conventional staining for light microscopy and by scanning electron microscopy.L cells grow indefinitely on combinations of equal concentrations of glucose and galactose, xylose, or mannose. There appear to be no significant differences in growth rate on glucose compared to the combinations of sugars cited. Cells subcultured from glucose to the combinations while undergoing rapid multiplication show marked morphologic changes by light and scanning electron microscopy within 36 hr.Of particular note are the loss of microvilli; flattening of the cells; assumption of polygonal shape; prominence of nuclei and nucleoli; and changes in the structure and distribution of filopodia. Virtually all cells in the population exhibit the changes noted. 相似文献
9.
J.G.S. Speers † A. Gilmour † T.W. Fraser R.D. Mccall 《Journal of applied microbiology》1984,57(1):139-145
Ethanol dehydration followed by argon replacement induced drying (ARID) was found to be a suitable method for the preparation of glass, stainless steel and rubber surfaces which had been in contact with inoculated milk and which were to be examined using scanning electron microscopy (SEM). This technique was used to examine samples of all three materials which had been subjected to both single and repeated inoculation with whole milk containing a Pseudomonas sp. or a Micrococcus sp. and incubated for various periods. Some samples were also prepared for SEM using a cryofixation technique. The Pseudomonas sp. was found to proliferate on glass and stainless steel surfaces but not on rubber. Due to the clumping tendency of the Micrococcus sp. proliferation of this organism was more difficult to assess accurately. In general there was no difference in results obtained between single and repeated inoculation. Various factors which may have aided attachment of micro-organisms to surfaces were identified viz. , surface channels present in stainless steel, milk deposits and the production of extracellular material. The value of using both the cryofixation and chemical preparatory techniques for the identification of artifacts is discussed. 相似文献
10.
11.
Scanning electron microscopy of Drosophila 总被引:2,自引:0,他引:2
12.
13.
14.
M A Ali H J Wagner 《Revue canadienne de biologie / éditée par l'Université de Montréal》1976,35(4):199-210
The morphology of the retinas of the goldeye Hiodon alosoides (fam. Hiodontidae), the brook trout Salvelinus fontinalis (fam. Salmonidae), the yellow perch Perca flavescens and the walleye Stizostedion vitreum (fam. Percidae) was studied by SEM. Semi-thin plastic sections of the same retinas were also examined for comparison. Contrary to observation of earlier authors the goldeye retina was found to possess both rods and cones; in the case of the other three fishes' retinas, present observations correspond to previous ones, adding only details. SEM gives an impressive, three dimensil view of the gross surface features of the retinas. Shrinkage during the processing of the specimens for SEM, while not altering the general topography, does induce artifacts in both plexiform layers. 相似文献
15.
16.
Internal anatomical features of developing chick embryos can be examined using the scanning electron microscope in embryos that have been sectioned at varying levels. Standard paraffin sectioning techniques are used. After removal of paraffin, embryos are dried by the critical point method and examined. The resulting scanning electron micrographs have proved to be exceptionally useful in teaching anatomy of embryos. 相似文献
17.
18.
Electron microscopy has revealed that in Bulinus guernei (Gambian strain) snails infected with Schistosoma haematobium (Egyptian strain) daughter sporocysts and cercariae, two kinds of hemocytes called granulocytes and hyalinocytes are found associated with the sporocysts. Granulocytes are small, numerous, plumbophilic, and amoeboid. They contain lysosome-like granules. Hyalinocytes are large, sparse, less plumbophilic than granulocytes, and have intracellular microfilaments (about 9 nm wide), and few or no pseudopods. They are devoid of lysosome-like granules. Granulocytes and hyalinocytes infiltrate near sporocysts, but only granulocytes interact with sporocyst microvilli by contact. Granulocytes induce a restricted multilamellated encapsulation reaction. Extracellular microfilaments (about 12.5 nm wide), with a regular transverse structure pattern of about 50-nm periodicity, frequently are found along the outer surface of granulocytes located adjacent to sporocysts. Intracellular filamentous structures and a prominent glycocalyx also are features of the seemingly more active granulocytes contiguous with sporocysts. Cell adhesions may occur between surfaces of (1) granulocytes and sporocysts, (2) interdigitating pseudopodial processes of capsular granulocytes, and (3) granulocytes and hyalinocytes. 相似文献
19.
20.
The morphology of conidia in 211 species and 12 varieties belonging to the genus Penicillium Link ex Gray have been studied and compared.According to surface ornamentation, conidia have been classified into six groups: A, smooth-walled (7% of the species); B, delicately roughened (13%); C, warty (28%); D, echinate (10%); E, striate with low irregular ridges (36%); and F, striate with scarce high ridges or bars (6%). Whereas the first two groups are closely related in both shape and average size, a gradual reduction was observed in size and in the length/width (l/w) ratio in the remaining groups. Echinate conidia were globose, having the largest average size. Only four species produced conidia not surpassing 2 m in diameter. Maximum length observed was 8 m, and most elongated conidia had a l/w ratio of 3.5. Forty per cent of the species studied had globose conidia.Conidia of the monoverticillate species were generally smaller, more globose and frequently with ridges. In the Asymmetrica, the conidia were generally larger, and showed ridges in comparatively few species. Conidia of the Symmetrica, which were frequently striate with ridges, presented the most elongated forms. The largest average size was found in the conidia of the Polyverticillata which were generally warty. Finally, we have considered the variations in surface ornamentation of conidia during the evolution of the genus Penicillium and drawn attention to their possible relationship with certain habitats and ways of conidial dispersion. 相似文献