Metabolic pathways of the fossil dinosaur bones. Part IV. Modes of linkage between osteocytes and a variety of nexuses of osteocytes processes.

Examinations were carried out on the fossil dinosaur bones 80 million years old. Samples for examination were prepared with specially elaborated methods. The light, transmission electron, and sanning electron microscopic images showed the spatial distribution of osteocytes with the system of processes as well as by thin and short ones. The axial processes, retaining the same diameter along their entire course, usually connected the polar parts of the osteocytes which frequently lay considerable distance apart. Such connections were of two kinds. In one case the link was attained by catoplasmic continuity. In the other, the processes belonging to one osteocyte came into contact with definite spot of plasmalemma of another osteocyte by means of a terminal, club-shaped widening, the so called contact body. This spot looked like a hollow or a conical protuberance. In this type of contact there were always tiny apertures between the contacting elements. Moreover, three types of contact, especially between thin processes, were distinguished, i.e. "end to end", "side to side", and "end to side". It seems that direct connections achieved through cytoplasmic continuity are utilized in rapid exchange, which may be indicated by the thickness of processes and the lack of a membranous barrier. The remaining, indirect links (with participation of membranes) though varied in the type of contact seem to fulfil identical functions.