Studies on the Blood Supply to Certain Regions in the Lumbar Part of the Spinal Cord

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Abstract
Summary.: The paper deals with the special vascularization studied in the anterior horn of the medulla, mainly in rabbits.In the first part it is shown that the cells in the periphery of the anterior horns are more resistant towards lack of oxygen produced by occlusion of the abdominal aorta than the central cells. Since this is true both for nerve cells and, after prolonged occlusion, also for glia cells the difference must be due to a difference in the blood supply.In the second part of the paper it is shown by means of radio sodium that a very slow circulation takes place in the anoxaemic part of the medulla during occlusion. The exchange of blood in the capillaries normally requiring less than a minute now takes an hour or more.In the third part of the paper it is shown by means of injection preparations that there is no difference in the density of the capillary network between the center and the periphery, but that the arteries split up into capillaries mainly at the periphery while the veins are formed mainly near the center.The tissue best resisting the occlusion lies therefore close to the arterial ends of capillaries and the least resistant close to the venous ends, and with the extremely slow flow during occlusion the peripheral cells can appropriate most or all of the available oxygen.The placement of a cell relative to the course of a capillary from the artery to the vein is essential for its oxygen supply when the circulation is much reduced by occlusion.The experiments of EINARSON and RINGSTED on long standing lack of E vitamin in rats point to the conclusion that this relation may also be significant for rapidly diffusing substances of very low concentration at normal rates of circulation, since it is shown that the peripheral cells in the anterior horns of the medulla innervating extensors and supinators (anti‐gravity muscles) better resist an almost complete lack of E vitamin than the cells in the central part (adductor and flexor muscles).