Cutaneous arteriovenous anastomoses present in the tail but absent from the ear of the rat.

Histological evidence has been presented for the existence of arteriovenous anastomoses in the rat tail. Similar structures, however, could not be found in the rat ear. The validity of the histological techniques was proved by the demonstration of an abundance of arteriovenous anastomoses in the rabbit's ear. In view of this and other recent evidence, it is concluded that the rat could be a useful model for comparative studies of blood flow in skin with and without arteriovenous anastomoses.