LECTIN INTRAVITAL PERFUSION STUDIES IN TUMOR-BEARING MICE - MICROMETER-RESOLUTION, WIDE-AREA MAPPING OF MICROVASCULAR LABELING, DISTINGUISHING EFFICIENTLY AND INEFFICIENTLY PERFUSED MICROREGIONS IN THE TUMOR

Intravital lectin perfusion was combined with computer-guided scanning digital microscopy to map the perfused elements of the vasculature in tumor-bearing mice. High-precision composite images (spatial precisio n 1.3 mu m and optical resolution 1.5 mu m) were generated to permit e xact positioning, reconstruction, analysis, and mapping of entire tumo r cross-sections (c. 1 cm in diameter). Collation of these mosaics wit h nuclear magnetic resonance maps in the same tumor plane identified s ites of rapid contrast medium uptake as tumor blood vessels. Digitized imaging after intravital double labeling allowed polychromatic visual ization of two different types of mismatched staining. First, simultan eous application of two lectins, each bearing a different fluorochrome , revealed organ-specific differential processing in the microvascular wall. Second, sequential application of two boluses of one lectin, be aring different fluorochromes successively, distinguished between doub le-labeled microvessels, representing efficiently perfused vascular se gments, and single-labeled microvessels, with inefficient or intermitt ent perfusion. Intravital lectin perfusion images of blood vessels in the vital functional state thus highlighted biologically significant d ifferences in vessel function and sewed as high-resolution adjuncts to MR imaging.