GLOMERULAR HEMODYNAMICS AND VASCULAR STRUCTURE - PATTERN AND DIMENSIONS OF A SINGLE-RAT GLOMERULAR CAPILLARY NETWORK RECONSTRUCTED FROM ULTRATHIN SECTIONS

This paper presents a quantitative study of a model of a rat glomerulus reconstructed from electron micrographs of subserial ultrathin sections. The entire capillary network is graphed, and the diameters and lengths of the capillary segments of the network are recorded, along with the computed resistance of each capillary segment to blood flow. These observations in turn are interpreted in relation to the theory of hydrodynamic flow through cylinders with permeable walls: Bounds are calculated for the pressure drops between the nodes of the network and the efferent arteriole, given the afferent and efferent blood flow. When recently published estimates of single-nephron afferent and efferent plasma flow of the Munich-Wistar rat were used in these calculations, a minimum pressure drop between afferent and efferent arteriole of 2.92 mm Hg was computed. This corroborates studies which suggest that filtration equilibrium is attained in the Munich-Wistar rat. © 1979.