A morphological study of the size of the vascular compartment of the carotid body in a non-human primate (Cercopithecus ethiopus), and a comparison with the cat and rat.

The carotid bodies from 5 adult non-human primates (mean body weight 2.9 kg) were perfusion-fixed at normal arterial blood pressure with 3% phosphate-buffered glutaraldehyde. Serial 5-microns sections were cut, stained, and, using an interactive image analysis system, determinations were made of the volumes of the carotid body and of its vascular and extravascular compartments. The total volume of the carotid body was, on average 0.21 mm3, the total vascular volume contributing 9.7%. The small vessels (5-12 microns diameter) comprised 5.4% of the total volume of the carotid body, or about 56% of the vascular compartment; these estimates were similar to values obtained for the cat and rat. The mean small vessel endothelial area, per unit of extravascular volume (which is assumed to consist largely of type 1 and 2 cells) was 61.8 mm-1 in the primate and 69.7 mm-1 in the cat. A value was not available for the rat. Estimates of the carotid body tissue specific blood flow were 31, 61 and 104 ml/min/100 g organ tissue in the primate, cat and rat, respectively. It was emphasised that these values were not to be confused with estimates of carotid body specific blood flow based on values for total organ blood flow and the dissected weight of the organ.