EXAMINATION OF INJECTED SPECIMENS BY CONFOCAL LASER-SCANNING MICROSCOPY AND SCANNING ELECTRON-MICROSCOPY

Although corrosion casts commonly examined by scanning electron micros copy (SEM) offer good insights into the general arrangement of the mic rovasculature of certain organs, no information can be obtained from s uch specimens on special morphological data or dynamic events. Thus, m ost investigators are obliged to make their interpretations of cast st ructures only on the basis of indirect criteria. A synopsis, which con siders the most important data in that respect, is given for the blood and lymphatic microvessels. Moreover, a methodological approach is in troduced, based on the application of fluorescent resin, which allows the examination of cast structures in uncorroded specimens together wi th the surrounding tissue by confocal laser scanning microscopy (CLSM) . When two differently stained resins are injected at different sites, e.g., Mercer-fluorescent yellow into an artery and Mercox-rhodamine i nto the interstice, blood vessels and lymphatics can be well distingui shed. In lymph nodes, the system of lymphoid spaces and that of intran odal sinuses can be separately represented with the same technique. Ap plications and advantages of the CLSM method, which is a useful tool f or an extended interpretation of corrosion casts in SEM, are shown in cast specimens from tongue, skin, and liver in rats. In this study, bo th corroded and uncorroded specimens were considered. In addition, a n ew approach is demonstrated which combines casting technique and fluor escence microscopy with investigations carried out under experimental conditions. This allows the examination of microvascular casts togethe r with labelled cells in liver and spleen in a state of phagocytosis.