The fluorescent images of decorated microtubules in fibroblasts and osteoblasts
that have been described above were probably obtained from portions of scales where
only the osteoblast and/or fibroblast layers remained attached to scales. Evidence for
this was obtained from light-microscopical examination of Methylene-Blue-stained
1 ¡1 m thick resin sections of non-decalcified Brachydanio scales and associated cells
that had been removed from fishes in the same way as scales prepared for
immunofluorescence studies (see Materials and Methods). In many regions of most
scales the epidermal and dermal cells had sloughed away and only some regions of the
fibroblast and osteoblasts cell layers shown in Fig. 1 remained attached to scales.
However, layers of epithelial cells remained attached to the osteoblast layer of each
scale for distances of up to 0-5 mm from the posterior edge of a scale. This was
apparent in immunofluorescence preparations. The epithelial layers exhibited a
fairly pronounced and diffuse fluorescence, which was probably due to uneluted nonspecifically
bound antibody. It was sufficiently substantial to mask fluorescent
images of decorated microtubules that might otherwise have been discriminated in
cells associated with the most posterior portions of scales.