In 1875, K8ster remarked that &dquo;the vasa nutritia (of veins) are extraordinarily more numerous than is ordinarily represented, and supply quite small veins, whose wall one thinks would surely be without vessels.&dquo;' Following these observations, the blood supply of the vein wall received little attention, although references to the vasa vasorum of veins can be found in the earlier literature.'-' On the other hand, the vasa vasorum of arteries have received considerable attention, and there have been numerous attempts to correlate disorders of the vasa vasorum with arterial pathology. More recently there has been a resurgence of interest in vasa vasorum of veins because of the increasing use of vein grafts to by-pass arterial blocks.Lepehne,l in 1919, first employed the benzidine reaction of hemoglobin for the purpose of staining hemoglobin specifically in tissue sections, and he noted that the resultant picture may resemble that obtained by injection of the vessels. O'Neill,' in 1947, first used the method to study vasa vasorum of veins, and he found there was a rich network in the adventitia, but he could not demonstrate them in the media and intima.During an investigation into the histology of canine autogenous vein grafts, it was found that ingrowth of vasa vasorum into the graft wall occurred despite attempts to exclude them.' These studies led to the present attempt to define vasa vasorum of veins more precisely. METHODThe benzidine and orthotolidine staining techniques were used to demonstrate the vasa vasorum. The method used was essentially that employed by 0'Neill;6 however, for the thicker-walled human long saphenous vein, orthotolidine was substituted for benzidine. Benzidine reacts with hydrogen peroxide, the reaction being catalyzed by hemoglobin, and red blood cells are stained brown. Thus only those vessels containing red blood cells are outlined.The veins examined included femoral and jugular veins and the inferior vena cava removed from dogs under general anesthesia; the long saphenous vein removed from human patients under local anesthesia during operations for varicose veins; human femoral veins obtained at postmortem ; and femoral and long saphenous veins taken from dissecting room cadavers and thus preserved in fixative. The diameters of vasa vasorum were measured with a traveling wire eyepiece micrometer (Zeiss)

A case of a woman who passed seven gall-stones 'per vias naturales' is presented. At subsequent operation for painful jaundice the portal vein was found to lie in front of the common bile-duct, although in its lower part it was retroduodenal.

The clinical history is presented of a 46-year-old woman with a permanently distended left external jugular vein which passed anterior to the clavicle instead of entering the subclavian vein just superior to the clavicle in the usual manner. For cosmetic reasons the vein was excised. Embryologically, the vein passing anterior to the clavicle was a persistent jugulocephalic vein. This is a normal venous channel which usually disappears after an anastomosis develops between the cephalic vein and the subclavian vein, inferior to the clavicle.

&dquo;The small laboratory animals have proved themselves somewhat lacking in value for the study of vascular disease, as well as for the demonstration of the means by which the vessel walls are nourished. It seems that the larger animals might offer better material for this purpose.&dquo;' This statement, made in 1938, may explain why most of the morphological and experimental work on vasa vasorum has been done on larger animals, especially the dog. However, the rat has been used in arterial autograft studies,' and although the depth of penetration of the vasa vasorum of the rat abdominal aorta has been mentioned briefly/,4 there are no detailed reports on the vasa vasorum and none on the anatomy of the blood supply of the inferior vena cava in that species. The present study aims to describe those features. Materials and MethodsTwenty-eight adult male Sprague-Dawley rats, weighing from 340 g to 595 g, were heparinized with 1000 IU/kg5 of heparin given intraperitoneally before perfusion. A cannula was inserted into the thoracic aorta or left ventricle, and each animal was perfused with heparinized saline followed by a 5% solution of India ink in saline which had previously been filtered through an 0.8 jum millipore filter. The perfusions were carried out at 110 mm Hg constant pressure.3 3The earlier specimens were fixed in 10% neutral formalin, and the abdominal aorta and inferior vena cava were dissected, photographed, and examined histologically. Later specimens were treated with the smooth muscle relaxant papaverine, 10-7 g/MI,5 then fixed in Bouin's solution and examined histologically, using hematoxylin and eosin and aldehyde fuchsin stains. The vasa vasorum and the aorta were measured with a Zeiss traveling wire eyepiece micrometer calibrated with a stage micrometer.