The azygos vein system in the rat.

The adult pattern of the azygos vein system of various mammals has received the attention of many early investigators (Eustachius, 1561 ; Bardeleben, 1848 ; Marshall, 1850; and Morrison, 1879). Since there has not almways been agreement among these workers in the patterns described, attempts were made by some of them to try to correlate the patterns on a developmental basis (Barcleleben, 1848 ; Marshall, 1850; and Parker and Tozier, 1897). Tihey ( 'B), Kampmeier ( ' la), Sabin ( '14, '15), and Reagan ('19) each described the development of the azygos system of a different mammal. Although there was partial agreement on certain aspects of the embryology, it was not until recently that there has been general accord. Since one of the more significant contributions to the development of the azygos system in the rat (Strong, '36) has never appeared as a journal article and is procurable only as a thesis from the Indiana University Library, it will be included and related to the present description of the adult pattern.