Morphology and histology of human and canine internal thoracic arteries

Background. We evaluated human and canine internal thoracic arteries (ITAs) to determine whether the latter is valid for studies relevant to clinical use. Methods. We studied 19 human ITAs obtained from 1 female and 14 male victim s of recent fatal accidents who had no evidence of cardiovascular disease ( mean age 39 +/- 19 years; range = 15 to 79 years), and ITAs of 21 randomly- selected mongrel dogs of both sexes, weighing 18-40 kg (average = 24.3 +/- 5.7 kg). Specimens were fixed in formalin at a controlled pressure of 120 m m Hg, before extensive assessment that included intimal thickening, conditi on of the internal elastic lamina, and number of medial elastic lamellae an d vasa vasorum. Results. The canine morphology and histology were similar to the human ITAs , but there was no intimal hyperplasia, and the media and adventitia were t hinner (ITAs of humans older than 40 years had significant increases in med ial thickness, as well as in overall length). Morphologically and histologi cally, the left and right canine ITAs were almost completely the same. Conclusions. Canine ITAs are valid for bilateral comparative studies and ar e a useful tissue source and model for clinically-relevant experimental stu dies. (C) 1999 by The Society of Thoracic Surgeons.