COSAS 2.0--a Macintosh-based stereological analysis system

Digital three-dimensional models of Drosophila development

Digital models of organs, cells and subcellular structures have become important tools in biological and medical research. Reaching far beyond their traditional widespread use as didactic tools, computer-generated models serve as electronic atlases to identify specific elements in complex patterns, and as analytical tools that reveal relationships between such pattern elements that would remain obscure in two-dimensional sections. Digital models also offer the unique opportunity to store and display gene-expression patterns, and pilot studies have been made in several genetic model organisms, including mouse, Drosophila and Caenorhabditis elegans, to construct digital graphic databases intended as repositories for gene-expression data.

Complete chromogen separation and analysis in double immunohistochemical stains using Photoshop-based image analysis

Simultaneous detection of two different antigens on paraffin-embedded and frozen tissues can be accomplished by double immunohistochemistry. However, many double chromogen systems suffer from signal overlap, precluding definite signal quantification. To separate and quantitatively analyze the different chromogens, we imported images into a Macintosh computer using a CCD camera attached to a diagnostic microscope and used Photoshop software for the recognition, selection, and separation of colors. We show here that Photoshop-based image analysis allows complete separation of chromogens not only on the basis of their RGB spectral characteristics, but also on the basis of information concerning saturation, hue, and luminosity intrinsic to the digitized images. We demonstrate that Photoshop-based image analysis provides superior results compared to color separation using bandpass filters. Quantification of the individual chromogens is then provided by Photoshop using the Histogram command, which supplies information on the luminosity (corresponding to gray levels of black-and-white images) and on the number of pixels as a measure of spatial distribution. (J Histochem Cytochem 47:119-125, 1999)

Computer simulation as a tool in evaluating intracellular spatial arrangement of an organelle using random section data

A random profile of a cell gives a highly biased presentation of the location of various organelles within an intracellular space. The technique combining mathematical modeling and computer simulation presented here is aimed to overcome this bias and interpret intracellular spatial arrangement of an organelle using two-dimensional (2-D) observations from random sections. It allows to simulate random sectioning of a cell whose shape approximates to an ellipsoid of rotation, and to obtain the coordinates for the center of an organelle profile located within a cell profile. The pilot study was performed to investigate the influence of different three-dimensional (3-D) scattering patterns of an organelle on the coordinates of an organelle profile's center. Computer tests were carried out on a personal computer using the original software written in Pascal. It was ascertained that statistical properties of a sample of organelle profile's center coordinates allow for a quantitative estimation of some 3-D features, including the position of an organelle with respect to a cell center and specific characteristics of an organelle position (e.g., its fixity or randomness).

Osteogenic potential of cultured periosteal cells in a distracted bone gap in rabbits

Osteogenesis of cultured periosteal cells was investigated in a bone-defective gap that was created artificially by distraction in the tibia of 12-week-old rabbits. A 10-mm circumferential length of periosteum was stripped from each stump of the osteotomized tibia, and the tibia was distracted rapidly (2 mm/day), resulting in disturbance of callus formation. Periosteal-derived cells, which were isolated from the contralateral tibia, were introduced into cell culture, subcultured twice to a population of 5 x 10(7) cells, and then injected into the defective bone gap when distraction was complete. Following inoculation of the cultured cells, significant new bone formation in the bone gap was observed. The control group which did not undergo cell transplantation showed only slight new callus formation which is supposed to be formed by osteogenic cells from the bone marrow. The bone mineral content of newly formed bone between the distracted tibia was analyzed quantitatively on radiographs. Histologically, the transplanted cells initially formed a mass at the injected site and then gradually differentiated into bone tissue from the peripheral region. Bromodeoxyuridine immunohistochemical stain was utilized to investigate the localization of the transplanted cells. The present study confirms that the orthotopically implanted periosteum-derived cells facilitate osteogenesis in a bone defect created using distraction in rabbits.