计算机辅助的小鼠肾连接小管三维重建

Computer-assisted 3D Reconstruction of Mouse Connecting Tubule

目的探讨肾连接小管(CNT)过渡为集合管系的空间走行规律。方法灌流固定3只C57/BL/6J小鼠,取肾组织块并树脂812包埋,从肾被膜到肾乳头共得到2000张2.5μm厚的连续切片,显微镜图像数字化并配准,计算机程序追踪38条CNT走行并测量其长度。结果来自长髓袢肾单位的CNT在胃皮质中上行,沿途与5～6条短髓袢肾单位CNT相互吻合成弓形管,弓形管或部分来自最浅表皮质的CNT在皮质浅层与集合管汇合。CNT各自走行约150～500μm,弓形管长度为600～900μm。结论肾单位只在皮质浅层经CNT或经弓形管汇入集合管系,集合管在穿过中层和深层皮质时不再有新的肾单位加入,提示肾小球滤过液在集合管下行过程中不再接受来自于其他肾单位的滤液,重吸收功能不受任何肾单位的影响。

Objective To study the spatial arrangement of mouse connecting tubules（CNT）and their transition to collecting duct system.Methods The renal tissues of three C57/BL/6J mice were fixed by perfusion and embedded in Epon 812.Totally 2 000 consecutive sections with the thickness of 2.5 μm were obtained from the renal surface to the papilla.The serial images under microscope were digitalized and aligned.Thirty eight CNT were traced with a series of computer programs.Results The CNT from long loop nephron ascended towards renal capsule and merged with 5 to 6 CNT from short loop nephrons to form the so-called arcade,while the latter or some of the CNT from the superficial cortex directly drained into the collecting duct in the superficial cortex.The lengths of CNT and the arcade ranged from 150 μm to 500 μm and 600 μm to 900 μm respectively.Conclusion The arcade or CNT drains into collecting duct only at superficial cortical level,which suggests that the reabsorption of the glomerular ultra-filtration in collecting ducts keeps unaffected when collecting duct runs through middle to deeper cortex.