Geometric similarity of aorta, venae cavae, and certain of their branches in mammals.

The diameters of the aorta and venae cavae at various points throughout their lengths, the diameters of their major branches, and the lengths of various aortic and vena caval segments were measured in plastic corrosion casts of the arterial and venous systems of the normal adult mouse, rat, rabbit, dog, goat, horse, and cow, extending over a body weight range of 38,000-fold (arterial) and 1,100-fold (venous). It is shown that the diameters and lengths of these vessels are described by power-law equations relating the particular diameter or length to body weight (BW) raised to a particular diameter or length to body weight (BW) raised to a particular power, i.e., diameter = a BWb. Equations for the diameters and lengths of the vessels are given for slightly distended vessels and for vessels distended in the physiological range.