摘要：目的：基于肾单位数字三维重建，阐明长髓袢肾单位细段超微结构和各型上皮分布范围。方法：采用C57 小鼠肾组织连续半薄切片，数字三维重建，进行管状追踪，进行长髓袢肾单位细段不同类型上皮超微结构分析和分布。结果：长髓袢肾单位细段上皮分为2、3、4三型，其中2 型又分为2a、2b、2c 三个亚型。2 型上皮约占整个细段的（53.51±5.05）%，3 型占（38.47±3.06）%，余下的为4 型。2 型上皮中，2a 最为复杂弯曲，2b 和2c 上皮结构相对简单。结论：长髓袢肾单位细段的超微结构和不同上皮分布规律，提示与其区域或节段性的离子运输密切相关，是肾髓质渗透梯度形成的重要原因。
Ultrastructure of mouse thin limbs of Henle's loops based on erials sections and 3D reconstuction
WEN Yu, ZHAI Xiaoyue
(College of Basic Medical Sciences, C 5 hina Medical University, Shenyang, 110001)
Brief author introduction:WEN Yu(1974), Female, Associate Professor,Histology.
Abstract: Thin limbs of the long looped nephrons (LLN) are of heterogenic ultrastructure and ransportation, which is important for formation of the gradient osmolarity in renal medulla and therefore the concentrated urine. Here presented a detailed description of the epithelia, including ultra-structure and length and location of the epithelial types and subtypes of the descending thin limbs(DTL), as well as ascending thin limbs (ATL), of the LLN. Three adult C57/BL/6J mice were used for
kidney tissue serial sections and computer assisted 3D reconstruction of nephrons. Based on tubular tracing, sections representing different epithelial types of DTL and ATL of the LLN were selected and re-embedded in Epon for the ultrastructural analysis. Three epithelial types, type-2, -3, and -4 in sequence are of their own ultrastructural features, running courses, and the spatial locations in renal medulla. Type-2 epithelium constituted the upper part of the DTL for a various distance, about
(53.51±5.05)%, located in the outer two thirds of the inner stripe of the outer medulla (ISOM); while type 3 epithelium lined the middle part (38.47±3.06)% of the DTL, started at the border of the outer two thirds and inner one third of the ISOM, ended at the lower 1/5 to 1/4 of the whole length of the DTL, at the various levels of the inner medulla (IM); and type-4 lined the last part of the DTL for various distances, and constituted the pre-bend part of the DTL and the whole length of the ATL. For the individual nephrons, the location of the transition between type-2 and -3 was almost consistent,while the transition of the type-3 and -4 was at the various levels of the IM. According to the ultrastructure, traditional type-2 epithelium was subdivided into type-2a, -2b, and -2c. Type-2a onstituted initial part of the DTL of LLN with highly complex ultrastructure and tortuous course for various distances, whereas type-2b and -2c were structurally less complex with less tortuous course,
compared with type-2a, and gradually transferred into type-3 around the border of outer and inner medulla (check). In conclusion, different epithelial types and subtypes along DTL and ATL were arranged in a regular sequence, but of various lengths and locations, suggesting regional or segmental transportation properties.
Key words: Kidney; DTL; long-looped nephron; epithelium; mouse
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