Chest morphology and azygos vein pattern in some species of primates

Abstract

On the material of 50 individuals representing various species of Primates (fig. 2) a pattern of azygos veins was observed. On grounds of previously accepted criteria four types of this pattern were distinguished (fig. 3). These types reach from single azygos vein (types I and II) to more complicated systems of veins with ramified hemiazygos and accessory hemiazygos veins (types II and IV). In genuses Cebus, Cercopithecus, Macaca, Papio, symphalangus and Pan attention was paid to a relation between chest morphology (width-depth index, number of ribs, substernal angle) and setting of azygos vein and its accessory vessels (fig. 1, table 1). It results that in primates having broader chests with broad subseternal angle doubled azygos vein dominates (genus Cebus). In primates having narrow, leptomorphic chests, single azygos vein is dominant (eg. genus Macaca) or even becomes a rule (eg. genus Cercopithecus). Chest morphology and pattern of veins in chimpanzees turned out to be similar to these observed in man. In the author's opinion, results obtained are in contrast with certain views holding that single azygos vein is a more progressive form than the doubled and ramified one.