3-DIMENSIONAL ORGANIZATION OF THE DEVELOPING VASCULATURE OF THE KIDNEY

Kidney function depends on a well-developed vascular system. Any impai rment of the blood supply disturbs the integrity and function of the o rgan. The differentiation of renal vessels has been investigation for many years, but little is known about the relationship between nephrog enesis and vessel development. In the present work the spatial organiz ation of the differentiating vessels was analyzed in precisely oriente d tissue sections and in optical sections acquired by laser scan micro scopy. Developing vessels as well as small capillaries were visualized with two endothelium-detecting antibodies. Small vessels running in p arallel towards the or gan capsule were detected in numerous cortico-m edullary-oriented tissue sections. Cross-sections of the nephrogenic z one showed a regularly arranged network, which was composed of cells d etected by both monoclonal antibodies. Parts of this network were loca lized in regions of the nephrogenic zone which have been assumed to be free of vessels or vessel-like structures for a long time. These resu lts were confirmed by the laser-scan-microscopic analysis of complete cortex explants. The extraordinarily regular arrangement of the endoth elial network in the nephrogenic zone allowed us to reconstruct the de veloping vascular system. The results presented here underline the clo se relationship between nephrogenesis and vessel development.