Figure 1.

a–c: Fluorescence double labeling of vimentin (green) and the proliferation marker Ki67 (red) in rabbit appendix using the Fab fragment technique. The section was incubated for 5 minutes with a mixture of an anti-vimentin antibody coupled to Alexa Fluor 488-labeled anti-mouse Fab fragments and an anti-Ki67 antibody coupled to Alexa Fluor 555-labeled anti-mouse Fab fragments. a and b show single channel fluorescences; the overlay of the two channels is depicted in c. The presence of vimentin is used to identify the membranous (M) cells (arrows) in the dome epithelium (de). In addition, fibroblasts and some other cells of the lamina propria (lp) contain vimentin and are thus labeled, whereas the opposed non-dome epithelium (nde) is devoid of vimentin-containing cells. The nuclei of proliferating cells (red, arrowheads), most of which are lymphocytes, are located in the cytoplasmic pockets of the M cells and in the lamina propria. Imaging was done in a confocal laser scanning microscope to depict the full quality of the labeling independent of optical limitations. d and e: Fluorescence view of rabbit appendix before (d) and after (e) laser microdissection of an epithelial region (asterisk) containing M cells. The section was labeled for vimentin in a single incubation of only 5 minutes. The quality of the micrographs is limited because they were taken in a low quality video camera of the microdissection system, and because optical imaging was done through the supporting membrane, which scatters light and produces autofluorescence. The latter is additionally induced by the laser beam at the margins of the microdissected area. a–c, 250:1; d and e, 70:1.