Optimization of perfusion decalcification for bones and joints in rats.

Decalcification of osseous tissues by perfusion of decalcifying solution into the vascular system has never been applied to the study of peripheral joints. To optimize perfusion methods, rats were decalcified by direct immersion or by one of two perfusion techniques: 1) systemic perfusion circulating the decalcifying solution from the ascending aorta; and 2) regional perfusion circulating the solution to the lower extremities from the abdominal aorta. The process of decalcification was monitored by serial radiographic examinations. After decalcification, bone and joint samples were stained for histochemistry and immunohistochemistry. With systemic perfusion, the decalcification time, dependent on weight, was markedly reduced compared to immersion. Regional perfusion decalcification was faster than all other methods studied. Microstructural preservation was comparable and immunostaining quality often improved. Applications of this work will improve the study of basic skeletal and articular problems.