[Heterotopic autotransplantation of the atrium in the rat. Effect on specific granules (author's transl)].

A technique for the autotransplantation of part of the right atrium in the rat kidney is described. The morphology of these grafts has been studied by light and electron microscopy at intervals varying from 15 to 346 days after transplantation. On light microscopy, the grafts show an organoid organization with a central cavity filled with blood surrounded by an endothelium around which concentric layers of cardiocytes are present. Electron microscopy reveals that the population of specific granules is not affected by transplantation. In the beginning, the cardiocytes show severe abnormalities of myofilaments, mitochondria and sarcoplasmic reticulum. The granular sarcoplasmic reticulum is much more abundant than in control cardiocytes. Most of these changes regress with time so that, after 346 days the transplanted cardiocytes appear almost normal. These experiments indicate that the specific granule population of atrial cardiocytes probably does not contain any appreciable amount of catecholamine and is not dependant on the nervous system or on a local stimulus.