[Do arteriovenous anastomoses of the olfactory mucosa exist? A light and transmission electron microscopy study in the rabbit].

Arteriovenous anastomoses were first mentioned more than 250 years ago. Since the original description, these peculiar vascular structures have been detected in almost every organ and tissue. In respect of the head and neck area, arteriovenous anastomoses have been mainly observed in the nasal mucosa of either humans or different animals and in the rabbit ear; the latter offers a unique chance for in-vivo studies using the ear chamber technique. Nevertheless, the existence of arteriovenous anastomoses in the nasal mucosa has often been denied. In the present study, we examined the endonasal vascular system of the rabbit by means of light- and transmission electron microscopy. No evidence for the existence of arteriovenous anastomoses could be found in the respiratory part of the nasal mucosa whereas in the deeper layers of the olfactory mucosa several vascular structures could be encountered that were similar to the glomerula digitalia of fingertips. It is emphasised that these vessels must be regarded as true arteriovenous anatomoses which might play a potential role in endonasal thermoregulation.