4D confocal microscopy for visualisation of bone remodelling.

Until recently it was very time consuming and difficult to make three-dimensional (3D) images of newly formed bone. With the advent of confocal technologies and increased computer power, 3D imaging is greatly facilitated. In this paper we demonstrate that enhanced confocal visualisation of newly formed bone is possible when bone is labelled in vivo sequentially with two osteotropic markers (xylenol orange and tetracycline). Computer-assisted reconstruction of the confocal optical sections was achieved through the use of the CONVEX Application Visualisation System (AVS). The computerised image data provides the researcher with ample flexibility in displaying the results. It was found that CSLM combined with AVS is excellent for visualising the remodelling process in three and four dimensions, in which the fourth dimension is time. With this approach visualised bone remodelling has become possible in a manner not easily achieved by other techniques.