. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 1382 VEIN. senting a vein from the oesophagus of an eel, magnified with low power, the vasa vasorum are seen to supply, indiscriminately, the vessel's coats and some small pellets of adipose tissue •which were near it. The arteries, nourishing a vein, ramify and divide principally upon, and among, its cellular coat, and form an elaborate plexus, with meshes having a general longi- tudinal direction, as seen in the figure; which, Fig. I ' Vasa Vasorum on external surface of a small Vein from the oesophagus of eel. (
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 1382 VEIN. senting a vein from the oesophagus of an eel, magnified with low power, the vasa vasorum are seen to supply, indiscriminately, the vessel's coats and some small pellets of adipose tissue •which were near it. The arteries, nourishing a vein, ramify and divide principally upon, and among, its cellular coat, and form an elaborate plexus, with meshes having a general longi- tudinal direction, as seen in the figure; which, Fig. I ' Vasa Vasorum on external surface of a small Vein from the oesophagus of eel. (Anyuilla acutirostris.) a a, vein ; b b b, small arteries supplying indiscrimi- nately the venous tunics and small masses of fat around the vein ; c c c c c, granules of adipose tissue. Natural injection. (Magnified about 18 diameters.) though drawn from a fish, sufficiently indicates the condition as found in man and mammals. The arrangement of these capillaries is, how- ever, subject to variety : in the vena cava of the cod, I have seen them long, straight, even, and perfectly parallel, with scarcely any trans- verse branching or anastomosis. The little venous trunks of the vasa vasorum usually open directly into the cavity of the vein, among whose tunics they have previously ramified, and their course is quite independent of the corresponding arteries. (Hen/e.) The vasa vasorum principally exist in the areolar tunic, but Henle states that they are to be found abundantly among the annular fibres of the veins.* The internal longitu- dinal coat is, in all cases, extra-vascular. Nerves of veins. — As far as our knowledge hitherto goes, veins differ remarkably from arteries in rantly being made the support of * In arteries, Weber has never found them in the circular tunic. Burdaeh states that he has found a few. nerves, and in seldom receiving any distribu- tion of them to their coats. It is a remark- able circumstance that veins appear, with slight exceptions, to be separat
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