[Observations of bone and incisor dentin of rabbits injected with rhodamine-labeled albumin by confocal laser scanning microscope].

The confocal laser scanning microscope (CLSM) is the most recently developed microscope using the confocal system and laser light source. This microscope is possible to create optical sectioning images from any depth of the specimen. In this study, the incorporation of rhodamine-labeled albumin (R-ALB) into the bone and incisor dentin was observed by CLSM. Male Japanese white rabbits were given an intravenous injection of R-ALB every two days for 10 days and sacrificed 3 days after the last injection. Transverse ground section of the tibia about 80 microns thickness showed the incorporation of orange-red fluorescence labeling into the endosteal surface as well as the Haversian system of bone. Each labeling line of R-ALB was clearly visible by CLSM compared with the normal fluorescence image. Three-dimensional reconstruction of the sectioning images showed the process of the incorporation of R-ALB into the bone and the complexity of the labeled pattern. R-ALB was incorporated into the incisor dentin and showed the periodic labeling pattern. The high resolution image of the periodic labeling pattern was observed by CLSM. These results indicated that CLSM is a valuable apparatus for studying the fluorescence labeling images of hard tissues.