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 victims 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 mm Hg, before extensive assessment that included intimal thickening, condition of the internal elastic lamina, and number of medial elastic lamellae and 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 thinner (ITAs of humans older than 40 years had significant increases in medial thickness, as well as in overall length). Morphologically and histologically, the left and right canine ITAs were almost completely the same. CONCLUSIONS: Canine ITAs are valid for bilateral comparative studies and are a useful tissue source and model for clinically-relevant experimental studies.