REGENERATION OF THE ENDOTHELIUM IN THE CANINE AND FELINE THORACIC-DUCT

Recent improvements in microsurgical techniques on lymphatic vessels f acilitated the treatment of lymphoedema. But it is becoming clear that a successful treatment of lymphatic disease has to be based on knowle dge of ongoing processes. Particularly, one of the important and uncle ar issue is cellular mechanisms of lymphatic regeneration. The regener ation of endothelial and the smooth muscle cells of the thoracic duct has been experimentally tested in vivo. The canine and feline thoracic duct was cryo-injured using 3 mm-based copper rod. Damaged endothelia l cells remained attached to the substrate and lost unthrombogenecy wi thin 48 hr. Adjacent EC restored the defect within 3 days by migration and proliferation. We observed that on the first day, the endothelial monolayer included some elongated multinuclear cells with blind silve r lines whereas, on the third day, they were replaced by a population of smaller ECs with numerous mitoses. Organization of the monolayer wa s restituted within 7 days. The newly formed endothelium was similar t o regenerating endothelium of arteries. In general, the clot that appe ared at the zone of injury on the second day was dissolved by the thir d day. Occasionally, the dense polymorphic clot adhered to the wall an d caused a delay in reendothelisation. Complete restitution of the tun ica media which involved migration and proliferation mechanisms accomp anied the endothelium regeneration.