Abstract: SA-PO553

A Morphogenetic Study of Murine Renal Collecting System Based on 3D Visualization

Session Information

  • Developmental Biology
    November 04, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Developmental Biology and Inherited Kidney Diseases

  • 401 Developmental Biology

Authors

  • Gu, Ling, China Medical University, Shenyang, Liaoning, China
  • Zhang, Jie, China Medical University, Shenyang, Liaoning, China
  • Chang, Shi-Jie, China Medical University, Shenyang, Liaoning, China
  • Wang, Kaiyue, China Medical University, Shenyang, Liaoning, China
  • Thomsen, Jesper Skovhus, Aarhus University, Aarhus, Denmark
  • Andreasen, Arne A, Aarhus University, Aarhus, Denmark
  • Christensen, Erik I., Aarhus University, Aarhus, Denmark
  • Zhai, Xiao-Yue, China Medical University, Shenyang, Liaoning, China
Background

The iterative bifid branching of ureteric bud (UB) lays basis for formation of the collecting system (CS), and for generation of nephrons as the tip of the UB induces nephrogenesis at the nephrogenic zone (NZ). A low nephron number is associated with adult defect, such as hypertension. Therefore, a full knowledge of the morphogenesis and the connections of CS with nephrons is crucial to understand the development of such adult defects. The present study provides a spatial morphologic transformation of UB branching into adult CS based on 3D reconstruction.

Methods

Serial paraffin and epoxy sections of 3 mouse kidneys from each of different embryonic (E) and postnatal (P) days were prepared. The branching paths of UB at E14.5, E17.5, and CS from P7 and adult kidneys were traced on aligned micrographs using custom-made software. The architecture of adult CS was first established for comparison of UB branching trees.

Results

1) The morphology of cortical CS was asymmetric. One ICT rapidly bended down into the juxta-medullary cortex from the main CD at the middle to superficial cortex forming an abrupt arcade. The other ICT went straight outwards to the superficial cortex and ran a certain distance beneath the renal capsule.
2) The connection of nephrons with CS in a specific temporospatial order. The earlier formed nephrons connected with the arcade in distal to proximal order along the trunk, while the later formed nephrons, connected with the ICT in proximal to distal order.
3) The association of UB branching morphogenesis with nephrogenesis was established. By E14.5 when the first mature nephrons appeared, the UB bifurcations reached up to 7 to 10 cycles, laying basis for adult CD formation. With time until P3, the tips at NZ increased in number, consistently inducing nephrogenesis instead of branching.

Conclusion

The CS is formed by more than one type of branching: 1) the traditional bifurcation for formation of CD; 2) lateral branching along the arcade for formation of the ICT and connecting segments; and 3) sprouting for formation of the CNT connecting directly with individual nephrons. This suggests that the number of the nephrons is closely associated not only to the iterative branching, but also to the formation of lateral and sprouting branches, the latter mainly occurred near NZ.

Funding

  • Government Support - Non-U.S.