Arteriovenous anastomoses at the carotid bodies of rats.

In 2 out of 390 carotid bodies of rats arteriovenous anastomoses (AVA) have been found. Both cases belonged to a group of 12 glomera carotici which were prepared using the semithin section technique. The AVA were found in the course of branches of the glomic arteries leaving the main vessel before its entrance into the carotid body tissue. Thus the AVA were placed near but outside of the carotid bodies. Histologically they showed a distinct extension of the tunica media caused by epitheloidly modified smooth muscle cells. Functionally these AVA could act as shunt vessels (Sperrarterien) that would be able to control the blood flow and/or flow distribution through their carotid bodies.