[Experimental heterograft tracheal transplants in animals. III. Light microscopic, scanning and electron microscopic findings (author's transl)].

In seven three-month old piglets, tracheal defects were created experimentally and Cialit-fixed human tracheal transplants were grafted at the site of the defect. The implants did well in five of the animals, and no signs of respiratory insufficiency (such as stridor, dyspnea or cyanosis) were found. 230-273 days after the transplantation, the animals were sacrificed and the tracheas removed. The transplants were then examined macroscopically and by light, scanning and transmission electron microscopy. Two questions arose: 1) What was the fate of the epithelium of the tracheal graft? It was then found that the host tracheal epithelium surrounding the graft resurfaces the graft. However, a series of morphological changes occur and are described in detail. 2) What happens to the grafted tracheal cartilage? It was found that the cartilage was replaced by thick connective tissue and scar. From the results of these studies, two conclusions could be drawn. 1) The repair of tracheal defects by means of Cialit-fixed human tracheal grafts is limited in those cases in which the newly formed connective tissue is not able to stabilize the tracheal tube. 2) The size of the heterologous tracheal transplant is limited to 6-7 cm2 in animal experiments.