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Petr Karen

Publications and source records attributed to Petr Karen.

3 recordsLinked to original sources

Three-dimensional reconstructions from non-deparaffinized tissue sections.

Three-dimensional (3-D) reconstruction from microscopic images represents a useful tool for the study of biological structures in embryology and developmental biology. However, it is usually necessary to cope with many difficulties connected with the preparation of specimens. In order to minimize mutual displacement of structures in successive sections, the applicability of non-deparaffinized tissue sections for 3-D reconstruction was tested. Chicken embryos were fixed and stained in toto with eosin and then embedded in paraffin. About 30-mum-thick non-deparaffinized serial sections were used for obtaining initial data for 3-D reconstruction of larger stacks of embryonic bodies using either fluorescence or confocal microscope. The same sections served for both collecting optical serial sections of mesonephros as source images for its 3-D reconstruction, and immunohistochemical detection of fibronectin, laminin and vimentin. It was found that sections with retained paraffin preserve the mutual spatial relationships of tissue components as well as provide an excellent differentiation of structure. It makes the process of 3-D reconstruction easier. The localization of the products of immunohistochemical reactions demonstrated the co-localization of fibronectin and laminin in basal laminas and the presence of vimentin in glomeruli and mesenchymal tissue. The use of non-deparaffinized sections represents a less time consuming and more effective alternative to thin histological sections for the purpose of 3-D reconstruction, and enables further application of material.

Animals↗

Three-dimensional computer reconstruction of large tissue volumes based on composing series of high-resolution confocal images by GlueMRC and LinkMRC software.

Computer-based visualization of large tissue volumes with high resolution based on composing series of high-resolution confocal images is presented. GlueMRC and LinkMRC programs are introduced, implementing composition of overlapping series of optical sections captured by a confocal microscope, registration and subsequent composition of successive confocal stacks. Both programs are using an interactive approach in combination with automatic algorithms for image registration. Further, the method for obtaining surface renderings of microscopical structure under study is described. For this purpose, structure contours visible in the sections are interactively digitized using a Colon plug-in module running in Ellipse environment. Then the coordinates of the contours are processed by special modules in the graphic programming environment IRIS Explorer and the structure surface is rendered. The method is shown on the 3-D reconstruction of the capillary bed of human placental villi and chick embryonic gut and its vascular bed.

Animals↗

Topological properties and spatial organization of villous capillaries in normal and diabetic placentas.

Spatial arrangement and complexity of the capillary bed of placental terminal villi were analyzed in 9 normal and 11 diabetic placentas. Specimens were taken by systematic random sampling, fixed and stained in toto, and embedded in paraffin. Fifteen fields of view were sampled systematically from 120-microm-thick sections of specimens and examined using a confocal laser scanning microscope. Series of thin optical sections of terminal villi and their developmental forms were recorded by the confocal microscope and used as initial data for three-dimensional visualization of the spatial arrangement of villous capillaries. Vascular topology and branching were studied by focusing through the villus, making a schematic drawing of the villous capillary bed and counting redundant capillary connections. It was found that the basic arrangement of villous capillaries is similar in both normal and diabetic placentas. Nevertheless, the proportion of simple forms of the capillary bed without redundant connections is significantly higher in normal placentas and the mean number of redundant connections per villus is significantly higher in diabetic placentas. It is concluded that both the longitudinal growth and branching of capillaries contribute to the increase in the placental capillary bed in late gestation and that the capillary bed of diabetic villi is more complicated due to more intense capillary branching.

Adult↗