ISSN:0368-3974    

DOI:10.1111/j.1365-2818.1959.tb04467.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SYNOPSISSome aspects of recent progress in microscopy are reviewed. The widespread development of histology at the electron microscope level has been made possible by technical advances such as the design of microtomes capable of cutting very thin sections, the development of suitable methods of fixation and embedding, and the invention of the glass knife.Some basic principles of microscopy are discussed and the origin of contrast is considered. It is shown that in many cases microscopic methods reveal the distribution of mass per unit area. This mass may be specific, as in the case of certain staining or absorption methods, or non‐specific, (i.e. total) as in the case of refractile objects and in electron microscopy. It is emphasized that no single method is capable of revealing all the physical and chemical properties of a specimen, and an examination under the microscope must be regarded as one of many possible experiment

ISSN:0368-3974    

DOI:10.1111/j.1365-2818.1959.tb04468.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SYNOPSISThe value of employing both light and electron microscopy in cytological research is discussed. It is pointed out, however, that depending upon the kind of problem being studied it may be necessary to employ a wide variety of experimental techniques. This is particularly true when attempting to relate structure to function. To emphasize this, and to present a synthesis of some recent work, observations made by the writer and collaborators on the testes of normal, irradiated and oestrogen‐treated rats are described. The following main results are reported: 1. The residual bodies, cast off by the newly‐formed spermatozoa, consist of basic cytoplasmic constituents; they are especially rich in R.N.A. 2. The residual bodies are phagocytosed by the Sertoli cells and degenerate. During the latter process their R.N.A. component is absorbed or dispersed. Their lipid, however, remains and probably constitutes the bulk of the lipid seen with the Sertoli cells during later stages of the seminiferous cycle. 3. A lipid cycle is shown both by the germ cells and the Sertoli cells. The germ cells contain most lipid during about stages 1–8. The Sertoli cells contain most lipid during about stages 9–14. The two cycles are essentially out of phase with each other. 4. The lipid of the germ cells, residual bodies and Sertoli cells, gives a negative reaction to Schultz's test for cholesterol. 5. High doses of radiation (10,000 rads; 50,000 rads) cause the germ cells to degenerate; they are then phagocytosed by the Sertoli cells. The degenerating germ cells form large amounts of lipid which comes to lie freely embedded within the Sertoli cytoplasm. This lipid gradually becomes markedly cholesterol‐positive. 6. Preliminary tests suggest that the cholesterol‐positive lipid of irradiated animals possesses progestin‐like activity. 7. During prolonged treatment with oestrogenic hormone, large amounts of lipid slowly accumulate within the Sertoli cells. This lipid gradually gives a strong positive cholesterol‐reaction.As a working hypothesis it is suggested that in normal animals the lipid within the Sertoli cells represents a steroid hormone or its precursor which it utilized by the germ cells at some particular stage, or stages, of their development. On this basis the residual bodies initiate the production of this hormone. Thus the well‐marked co‐ordination of spermatogenetic stages about a radial axis in seminiferous tubules of the rat may depend upon the phagocytosis of the residual bodies and the secretion of a steroid hormone b

ISSN:0368-3974    

DOI:10.1111/j.1365-2818.1959.tb04469.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

ISSN:0368-3974    

DOI:10.1111/j.1365-2818.1959.tb04470.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SYNOPSISAttention is drawn to the inadequacy of the standard methods of qualitative assessment of surfaces, particularly for translucent specimens in the magnification range intermediate between the light and electron microscopes. The advantages of certain unconventional methods, namely metal shadowing for light microscopy, reflection electron microscopy, and scanning electron microscopy are discussed.

ISSN:0368-3974    

DOI:10.1111/j.1365-2818.1959.tb04471.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

ISSN:0368-3974    

DOI:10.1111/j.1365-2818.1959.tb04472.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SYNOPSISThe paper is divided into three parts. It begins by comparing the relative merits of the optical and electron microscopes in the study of crystals, being particularly concerned with the problem of examining specimens in all dimensional ranges. Special attention is given to the discussion of electron diffraction, especially to diffraction effects observed in images, e.g. Bragg fringes and moiré patterns and the methods of identifying the Bragg reflections contributing to them (i.e. dark ground and ghost image techniques). In the second part of the paper, the use of the techniques described is illustrated in the field of polymer morphology. A brief review is given of the subject, emphasizing the special role that co‐ordinated optical and electron microscopy has played in its establishment. Spherulites, sheaves and fibrils, and single crystals are discussed. In these last, the phenomenon of folded molecular chains and its necessary consequence of distinct crystal sectors are introduced. Finally, some new work is presented concerning the effects of changing the temperature during the growth of polymer single crystals. Such treatment produces various striking growth habits for which some explanation is offered. More importantly, these habits provide new information concerning the growth of fold‐containing crys

ISSN:0368-3974    

DOI:10.1111/j.1365-2818.1959.tb04473.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

摘要:

SYNOPSISAn ultra‐violet microscope of high resolution, using radiation of wavelength 2570 Å, is described. This makes it useful to the electron microscopist for giving information about the concentration of nucleic acids in different parts of an organism. Three different types of application are described. Firstly, a comparison of ultra‐violet pictures with electron micrographs of identical bacteria(Mycobacterium phlei);secondly, a comparison of light microscope pictures of Feulgen‐stained organisms(Streptomyces cœlicolor) with ultra‐violet pictures as well as with electron micrographs of these bacteria at the same stage of growth. The third application concerns a comparative study in the ultra‐violet and electron microscopes of locust testis in order to assist in interpreting the electron microscope picture of the nucleus in these cells.The interference microscope was used for measuring accurately the thickness and refractive index of thin sections. A special grid for mounting thin sections to be measured in the interference microscope was designed. The method was used to investigate the effect of the electron beam on thin sections of four different embedding materials (Methacrylate, Araldite, Vestopal, Aquon). It was found that all sections become thinner, the loss of thickness ranging from 25–60 per cent according to the nature of the material and the amount o

ISSN:0368-3974    

DOI:10.1111/j.1365-2818.1959.tb04474.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

ISSN:0368-3974    

DOI:10.1111/j.1365-2818.1959.tb04475.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY

ISSN:0368-3974    

DOI:10.1111/j.1365-2818.1959.tb04476.x

出版商:Blackwell Publishing Ltd    

年代:1959

数据来源: WILEY