Ultrastructural demonstration of a connection between afferent and efferent juxtamedullary glomerular arterioles

Abstract

The ultrastructure of the vascular pole of the glomerulus was examined in different zones of the rat kidney. In the 'juxtamedullary' zone, the previous observation of a direct vascular continuity between afferent and efferent vessels bypassing the glomerular tufts was confirmed. The wall of the connecting vessel segment was built up by the so called juxtaglomerular lacis cells, the functional significance of which has hitherto been obscure. In the lacis cell groups of the 'cortical' zone, however, no vessel lumina were demonstrated.