Introduction: We did this study because there were a few studies about aorto-branch junction.
Methods: Four light microscope and electron microscope study, the abdominal aorta, renal artery, and the adjoining right and left renal arteries were dissected out from 4 neonate dogs.
Results: Based on the results, there is only one cell type in the tunica intima of endothelium in both arteries. In abdominal aorta, there were open connective tissue spaces, containing elastic fibers between the internal elastic membrane and endothelium. In renal artery, endothelial cells were attached directly to the internal elastic membrane. In the abdominal aorta tunica media, layers of smooth muscle cells alternating with elastic lamellae were observed, but in renal artery, the smooth muscle cells were close to each other and a small quantity of collagen and elastic fibers were found between them. There were more dense bodies in the renal artery smooth muscle cells compared to the abdominal aorta. The adventitia of the both arteries consisted of scattered fibroblasts and elastic fibers in tunica adventitia of renal artery were more than those in abdominal aorta. There were 2 orientations of smooth muscle cells at the junction of renal artery; circular form in tunica media and longitudinal form in the outer part of tunica media and tunica adventitia and it was similar to the structure of muscular veins.
Conclusion: aorta and renal artery in neonate dogs show some differences. These differences presumably reflect adaptation to the function of these 2 arteries.