摘要:

SUMMARYThe response of photographic emulsion layers to electron beam exposures is reviewed in simple terms, particularly for those energies used in conventional electron micrography. Emphasis is placed on the way many features of response are determined by the fact that a single electron serves to render several grains developable. In particular it is shown that the contrast is independent of emulsion/developer combination, the granularity is uniquely related to the speed, and the signal/noise ratio increases with exposure irrespective of the conditions leading to exposure increase. Demonstrations of these aspects are presented. Factors governing image spread are also outlined. The dependence of the minimum magnification for observation of details of a given size on this property is discussed.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1973.tb03782.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYIn a morphometric study of the peripheral glomerular basement membrane distribution curves of true membrane thickness were obtained. The measurements were made on photomontages of total glomerular cross‐sections.The distributions were always markedly right‐skewed. A transformation leading to normal distributions was sought. Transformation of basement membrane thicknessTtowas found to be optimal.The arithmetic mean,Th, of this reciprocal transformation was applied in the statistical analysis of the very earliest stages of diabetic glomerulopathy. It is also meaningful as regards the physiological role of the basement membrane as a filtration barr

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1973.tb03783.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYMeasurements of penetration on silicon and austenitic stainless steel have been continued using the same criteria as previously reported (Thomas, 1968) up to 2.5 MeV using the 3 MeV Toulouse electron microscope. The results show that penetration increases to about 14 μm at 2.5 MeV for silicon although the curve starts to flatten out above 1.5 MeV, but no significant gain was found for stainless steel ≃2μm at 2.5 MeV). Primary knock‐on damage occurs readily in both materials. The critical voltages for 440 silicon and 422 tantalum were measured, and both found to be 1.4 MeV (± 10 kV).Attempts to measure the variation of radiation damage with beam voltage in crystalline amino acids as indicated by the fading of diffraction patterns indicated that the damage rates apparently decrease as the voltage is raised to 2.5 MeV. However, it was not possible to determine this variation quantitatively because of difficulties in measuring the absolute values of the critical exp

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1973.tb03784.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYThe degree of irregularity presented by the 20–40 μm diameter depressions in adult human articular surfaces was measuredin vitro, using the scanning electron microscope (SEM), replication, stereo‐microscopy and profile recording techniques.Using stereo‐microscopy, the measured articular surface depressions varied from 0.9 to 15 μm in depth and the corresponding humps on the replicas varied from 0.3 to 8.9 μm in height. The heights of the replicated contours measured by the profile recording device varied from 0.2 to 5 μm. It was emphasized that, while these values give some indication as to the possible degree of surface irregularityin vivo, the actual contours in a living, load‐bearing joint may be quit

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1973.tb03785.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYA technique for the cytochemical demonstration in the electron microscope of glucose‐6‐phosphate dehydrogenase activity in malaria‐infected erythrocytes is described. Reaction product occurred as diffuse electron‐dense deposits of the formazan of MTT in the red cells. No activity was observed within the malaria parasites themselves, except in the contents of food vacuoles. The results of a series of control experiments are also de

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1973.tb03786.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYA study has been made of methods of fixing, staining, and embedding for electron microscopy the lamellated osmiophilic bodies (LOPBs) of the type II cells of the lung, which are probably connected with the lung surfactant. The preferred method for fixing and staining uses successively 2% glutaraldehyde, 1% osmium tetroxide, and a mixture of 10 vol M/40 lead nitrate with 10.5 vol M/60 potassium ferricyanide: all reagents are in cacodylate buffer. Unless the ferri‐cyanide is in excess, the sections show blotchy precipitation. The bodies are damaged by ethanol and 1:2 epoxypropane. Dioxan or (with a quick time schedule) acetone may be used as a dehydrant and thinner prior to Araldite embedding. Durcupan water‐soluble resin may also be used for dehydration and embedding; the preferred embedding mixture is: 5 ml resin A, 11.7 ml hardener B, 1.5 ml hardener C, and 0.4 ml plasticizer D, cured for 24–48 h at 60°C. Examination of LOPBs on a goniometer stage shows that they are composed of layers spaced at 4 nm, each lamella containing several such layers. Further evidence is adduced linking the LOPBs with the surfactant, and the application of the new methods to various problems involving the LOPBs is dis

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1973.tb03787.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYA variety of mammalian tissues have been prepared for electron microscopical examination by cryo‐ultramicrotomy. In conjunction with the ultrastructural investigation of the cellular and subcellular morphology of frozen sections, X‐ray micro‐analysis has been performed on various organelles in an attempt to determine their elemental composition and to monitor any variations in elemental concentra

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1973.tb03788.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYMicrofibrillar structures can be seen in ultrathin sections of cell walls which have been post‐stained with uranyl acetate and lead citrate. This stain is removable by washing, suggesting that a physical mechanism is involved. It is suggested that these structures are the cellulose microfibrils of the wall; they appear to be 3.5 nm in diameter and not fasciated into larger units. Freeze‐etching of untreated tissue supports this conclusion. These two techniques seem to have many advantages over methods previously used for the study of microfibril arrangement and struct

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1973.tb03789.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYNematodes and mildew‐infected barley leaves when examined in the scanning electron microscope after critical point drying (CPD) from sulphur dioxide (critical temperature 157–7°C) showed no obvious physical damage, but the specimens had a surface deposit which was probably heat damaged natural waxes. The nematodeCaenorhabditis elegansand clover roots (Trifolium subterraneum) showed no physical or heat damage after CPD from monochlorodifluoromethane (Freon 22, critical temperature 96°C). The hyphæ and conidia of unfixed mildew on barley were damaged after CPD from Freon 22, probably due to the Freon extracting lipids from the cell walls. Freon 22 was preferred for most specimens as it is cheap, easy to get and not very

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1973.tb03790.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYRed blood cells and bacteria have been viewed under the high voltage transmission electron microscope, using a controlled environment chamber. Red cell changes on introduction of an agglutinating serum into the environment and bacterial changes on addition of an antibiotic, were observed. The results are compared with those obtained by phase contrast light microscopy and the potentialities of the system discussed.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1973.tb03791.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY