Scanning electron microscopy of arteriovenous anastomosis in nasal respiratory mucosa.

Arteriovenous anastomosis (AVA) in nasal respiratory mucosa of humans and guinea pigs were studied with scanning electron microscopy (SEM) after removal of extracellular connective tissues by tryptic digestion and HCl hydrolysis. The shape of AVA in humans is different from that in guinea pigs. In guinea pigs, it is simple with no specific structure observed on the vessels. In humans, it is characterized by a spherical swelling at the intermediate segment. The Tunica media of the spherical body is formed by the aggregation of spindle-shaped cells and receives a rich nerve supply. These findings suggest powerful contractility of human AVA compared with guinea pigs. Arteriovenous anastomosis in human nasal respiratory mucosa may strongly influence arterial blood flow into the cavernosus sinusoid and determine the characteristic microcirculatory pattern in human nasal mucosa.