Tissue changes in chronic experimental lymphoedema in dogs.

Chronic lymphoedema was experimentally induced in the legs of dogs and studied with the electron microscope, including by quantitation. It was found that some cells (macrophages, fibroblasts and, to a lesser extent, lymphocytes) increased greatly in numbers and relative volumes. Collagen (and fat cells) also greatly increased in relative volume. The lengths of blood vessels and initial lymphatics were much greater in the injured tissue. The numbers of small vesicles and vacuoles rose greatly in both types of vessels. Both also had many open endothelial junctions--although no doubt from different causes. It is probably caused by excessive accumulations of proteins, so chronic lymphoedema is probably a form of chronic inflammation.