Three-dimensional visualization of the renal proximal tubules in developing mice / 解剖学报

ABSTRACT

Objective Adult proximal tubule ( PT ) is not only the segment most frequently involved in acute renal tubule injury, but also the easiest to repair. It may be consistent with the rapid growth and differentiation mechanism of this segment during the development of the kidney, while the developing information is insufficient. Therefore, we three- dimensional visualized the developing PT to analysis its spatiotemporal morphogenesis. Methods The kidneys were obtained from mice at various developing time point, embryonic day ( E ), postnatal day ( P ). The volume density of Claudin-2 positive PT in the cortex was measured using a stereological method in paraffin sections. After image recording and alignment of the serial sections, the spatial courses of the developing PT were traced and visualized in three dimensions using computer-assisted program. The length of the developing PT was calculated at the same time. Results The volume density of PT in the cortex of PI mice was significantly higher than that in the embryonic stage. Then it experienced a decline ( P3, P5 ), an increase ( start at P7 ) to a stable adult level ( P28 ). The tubular tracing showed that the lengths of developing PT and the number of convolutions of their convoluted part increased with the maturation, but lower than that of adultin E14. 5, E17. 5 and P5 PT in E14. 5 and E17. 5 mice were similar to that of adult with respect to general spatial courses. They were, however, significantly different from adult in the initial direction of PT and the arrangement of the straight part of PT in the medullary rays. While, it was in P5 that the spatial pattern of some PT was gradually approaching to the adult model. Conclusion This study demonstrated that the development of PT was consistent with the kidney development in terms of its volume density in cortex, length and spatial course. It started at the S-shaped body, kept throughout the embryonic period and continued to postnatal, ended at kidney maturation ( P28 ).