Microscopica acta最新文献

The usefulness of protein films denaturated and fixed with ethanol/ether as cytochemical model systems was investigated. Kinetics of staining with amido black 10B were analyzed as well as the spectroscopic properties of the protein-dye complex. The absorption coefficient of the complex was estimated. Data obtained so far are compared with both stained cells and the protein-dye complex in solution. Discussion focuses on the influence of fixation and the possibilities to use the films as systems for calibrating cytochemical stainings.

This communication presents observations on the ability of an aqueous solution of cresyl violet to demonstrate DNA in deparaffinised rat tissue sections from which RNA has been extracted selectively with 90% phosphoric acid at 5 degrees C for 40 min. An aqueous solution of cresyl violet was found to be highly unstable and, therefore should be used when freshly prepared. The peak of maximum absorption of stained nuclei has been found to be at 560 nm. Staining of the nuclei following extraction of RNA has been due to the phosphate groups of DNA which is found to be in a native state.

This paper described a new histochemical method for the detection of sulfhydryl groups in tissue specimens using 2,6-dichloroquinone chloroimide G.R. (Merck) after the reduction of its chloride groups of sodium thiosulfate. Ths proposed mechanism of the reaction, the procedures and the histological applications are described.

A tissue can often be characterized by size and shape of its nuclei. For several purposes the population of nuclei is analyzed by using tissue sections. However, the relationships between the distribution of the sizes of the nuclei and that of their sections are not self-evident. Therefore, the cutting of spheres was simulated on a computer in order to clarify the relationships in at least a simple system. As each combination of different spheres results in a specific distribution of sections, it is often possible to decide without any calculations whether an observed histogram of sections originates from a system of spheres of the same or of different sizes, or of non-spherical objects.

A highly sensitive electronic unit (called "silicon photo probe") is described, which enables registration of cellular motion phenomena simultaneous with their light microscopic observation. Changes in light intensity caused by movements of the living object are registered by means of a silicon photo diode (silicon blue cell), which can be mounted within the binocular tube of any type of light microscope replacing one of the oculars. Its application during investigations of oscillating contraction activity in Physarum is reported. Advantages and short-comings are discussed with respect to established photometric, tensiometric and infrared registration techniques.

A mathematical formulation is presented of the three dimensional distribution of intensity in the image of a bright point. Other equivalent formulations have been described before, but this one appears to have certain practical advantages. The formulation has been used in computer programs to provide tomograms and isophote contour maps of the intensity distribution. A following paper will describe the application of the formulation to differential interference contrast-microscopy.

Contrary to homogeneous tissues, "mixed" tissues or cell suspensions are composed of different cell individuals. They have been characterized as heterogeneous cell populations (composed of cells of different cytogenetical source) and heteromorphous or inhomogeneous cell populations (of cells of the same type but of different individual functional state). Certain problems may arise during ultrastructural morphometrical investigations of heteromorphous populations. Because of the different size of planes of sectioning of individual cells, morphometrical results should be treated by means of modifications of the t-test [4]. Furthermore, the unambiguous classification of individual cell profiles necessitates a conscious selection of cell profiles containing a nuclear profile. This non-random sampling approach leads to systematic errors of computed parameters for the whole cell as the nuclear volume fraction and the specific cell surface area which should be corrected. Besides correction procedures derived from regular geometrical models we have presented correction methods for cells with non-spherical nucleus and a cell surface with marked surface projections [13, 21]. On the other hand, on heteromorphous cell populations, more detailed information about functional events can be gained, in comparison the customary stereological mean values, by means of frequency distributions of morphometrical data of individual cell profiles as well as by correlation of data of different cell organelles.

The investigation reports on the use of safranine-SO2 and phenosafranine-SO2, prepared with N HCl or oxalic acid plus potassium metabisulphite, for staining rat liver sections following Feulgen procedure. It has been found that optimum staining of DNA-aldehyde molecules is possible with safranine-SO2 and phenosafranine-SO2, prepared with N HCl and potassium metabisulphite, upto a duration of one week after the preparation of the dye-reagents. Thereafter, staining intensity of the nuclei produced by the dye-reagents is gradually diminished. Staining of acid-hydrolysed sections is also possible with aqueous solutions of these dyes. Moreover, DNA-phosphate groups can also be stained with aqueous solutions of these dyes after selective extraction of RNA with cold phosphoric acid. The in situ absorption spectra of nuclei, stained for DNA-aldehyde molecules with safranine-SO2, phenosafranine-SO2 and aqueous solutions of these dyes, have been presented in this paper. Also presented herein are absorption data of nuclei stained with these dyes after selective extraction of RNA. It has been found that absorption-peaks of nuclei stained differently are different from one another. The implications of these findings have been discussed.

Stereology is a geometrically and statistically defined body of simple methods for estimating morphological quantities of three-dimensional (3-d) structures from measurements made on two-dimensional (2-d) sections. The straightforwardness and the strength of its theoretical basis is illustrated by some newer methods applied in experimental clinical research. Contrary to expectation, the reduction in information from 3-d structures to 2-d sections brings about only a minor increase in the statistical uncertainty of the central moments of most of the fundamental structural characteristics. The sole exceptions are the number of isolated structures and the degree of connectedness in 3-d space, structural quantities the importance of which is limited to the questions of (neo)genesis and communications, respectively. In general, the overall variation in morphometry is determined more by biological than methodological variation. Therefore, stereology is part of the broad spectrum of modern quantitation techniques the sensible application of which depends primarily on common sense in the experimental technique and in the definition of the biological question. The ease and the simplicity of the measurements contrasted by the still quite elaborate and difficult histological preparations of tissue mean that the automation of the measuring process alone is not sensible.