A STUDY OF BLOOD FLOW IN MINUTE VESSELS OF THE PANCREATIC REGION OF THE RAT WITH REFERENCE TO INTERMITTENT CORPUSCULAR FLOW IN INDIVIDUAL CAPILLARIES

Abstract

A method is described for the microscopic study of capillaries in the tissues in and adjacent to the pancreas in the living rat.In freely moving blood the red cells are distorted and orientated, along the line of flow, but the leucocytes usually remain spherical.An intermittent flow of corpuscles through individual capillaries was frequently seen, especially in the most narrow capillaries.This intermittency appears to be due to one or other of the following three passive mechanisms, of which the first two depend on the properties of blood itself as a non-uniform suspension:(a) Transient plugging by a leucocyte larger in diameter than the calibre of the capillary.(b) Intermittent plasma skimming.(c) Reversal of flow due to reversal of pressure gradient.The calibre of no part of a capillary was ever seen to change rapidly.Active contraction of a capillary or precapillary sphincter cannot be inferred merely from the finding of intermittent flow.Plasma skimming has been induced by slowing the flow through a branch.The mechanism is discussed and the possibility is considered of an unstable state in which intermittent plasma skimming could occur spontaneously.