BOWMAN'S CAPSULE CORRECTED: UNDISCOVERED VASCULAR CHAMBERS IN THE RENAL GLOMERULUS

Abstract

The structure of the kidney glomerulus, known since Bowman's description in 18571, is of arterial afferent capillaries leading to exchange capillaries and an efferent arteriole. While investigating the three dimensional structure of the glomerulus we discovered that this description is incorrect in adult human glomeruli. Serial section reconstruction of glomeruli perfused‐fixed under physiological colloid osmotic and hydrostatic pressures showed that afferent and efferent arterioles lead into previously undescribed ellipsoid, wide vascular chambers (VCs). From the afferent vascular chamber (AVC), 5–7 long, non‐branching, conduit vessels lead to the glomerular edge where branching occurs. Using multiphoton microscopy, a signal consistent with banded (fibrilar) collagen was seen in second harmonic generation mode in unfixed glomeruli in a region consistent with vascular chamber walls imaged by two photon fluorescence. Electron microscopy confirmed that a layer of banded collagen surrounds VC walls. Approximately thirteen highly branched, first order vessels (E1) converge on the efferent VC (EVC), which drains into the efferent arteriole. Complex vortical flow modelling predicted that the AVC acts as a plenum manifold, distributing and balancing blood flow/pressure to conduit vessels supplying blood to different glomerular lobules. These previously undescribed adaptations of glomerular vascular structure in humans could regulate haemodynamic pressure and flow in glomeruli, and their disturbance provide a new mechanism to explain kidney diseases.Support or Funding InformationThe Richard Bright Research Trust, Kidney Research UK (2014–2015) and the Medical Research Council G10002073 and MR/K020366/1This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.