小鼠短髓襻肾单位在外髓的分布

目的 肾外髓间质渗透梯度形成的机制与髓襻上皮转运功能及其毗邻关系有密切关系,本研究拟建立短髓袢肾单位在外髓的走行规律。方法C57/BL/6J小鼠3只,灌流固定后取肾组织块并树脂812包埋,垂直肾长轴连续半薄切片,从肾被膜到内外髓交界处,共得到1 200张2.5μm厚的连续切片,显微镜下获取数字图像,计算机配准,C语言编程,进而追踪来自皮质浅层和中层的120个短髓襻肾单位。结果 短髓襻肾单位的53%起于肾皮质外1/3,47%起于中间肾皮质。前者髓襻襻曲分布在外髓内带中部同一水平,其襻曲或完全由细段上皮构成,或由髓襻降支细段上皮与升支粗段上皮移行构成;来自中间皮质的短髓襻襻曲位于外髓内带内侧1/2的不同水平,其深度与其肾小球在中间皮质的深度成正比。其襻曲由髓襻升支粗段上皮构成,并在襻曲前构成约50~450μm长的髓襻降支。最深的襻曲在外髓内带弯曲走行。结论髓袢襻曲在外髓的位置及上皮类型不同,提示外髓不同区域的小管对超滤液重吸收的成分也有所区别,对外髓深部渗透梯度增高的形成产生一定的影响;而襻曲的位置和上皮构成与肾小球在皮质的位置相关,提示肾小球的滤过与肾小管的重吸收功能有整体的调节。     

小鼠肾近端小管的三维重建

目的 研究小鼠肾近端小管三维空间走行的特点及规律。 方法 C57/BL/6J小鼠3只,灌流固定后取肾组织块并树脂812包埋,垂直肾长轴连续半薄切片,从肾被膜到肾外髓外带共得到1 200张2.5μm厚的连续切片,显微镜下获取数字图像,计算机配准,C语言编程,追踪并三维重建58条近端小管走行。 结果 在皮质迷路中,近端小管起始段在离开肾小球后,均先向被膜方向走行约100～1 400μm后返折,在各自肾小球周围盘曲并占据相对独立的区域,很少和其他肾单位近端小管曲部区域重合。浅表皮质肾单位与中间皮质肾单位的近曲小管盘曲紧密,所占空间比近髓肾单位近曲小管小。在髓放线中,近端小管直部的走行有明显的层次：来源于浅表皮质肾单位的近端小管直部走行于中央,来源于皮质深部肾单位的近直小管则依次走行在其外围,皮质最深层的肾单位的近直小管几乎无直部。所有近端小管均止于肾外髓外带与内带的交界处,并移行为髓袢降支细段。 结论 小鼠近端小管的起始段、曲部和直部在皮质迷路与髓放线都有各自走行区间,其吡邻关系及所处生物学环境不同,这对肾近端小管不同节段对不同物质转运功能的生理及病理评估提供形态依据。     

小鼠肾脏髓襻细段发育的超微结构

目的：探讨小鼠肾脏髓襻细段发生发育及逐渐成熟过程。方法：应用光镜半薄切片和电镜超薄切片观察小鼠肾脏髓襻细段发育过程中的超微结构变化。结果和结论：细段出现于胚胎后期,生后逐渐发育完善。上皮由立方细胞逐渐发育成扁平细胞过程中,细胞凋亡起着很大作用。细胞凋亡高峰时间发生在生后七天左右。超微结构观察发现生后细段完善主要位于长襻肾单位的细段。结论：细段在胚胎晚期出现,生后发育。在这一过程中,特别是在细胞构筑过程中细胞凋亡起着重要作用。     

犬肾血管构筑及血管和肾小管相互关系——扫描电镜观察

使用同时显示肾血管和肾小管扫描电镜法及肾血管铸型扫描电镜法,观察研究了犬肾血管构筑及肾血管和肾小管相互关系。血管球内存在亚小叶微循环单位;血管球内存在直捷通路;迷路部血管和肾小管无明显的逆流配置;球后血管在肾皮质内有广泛吻合;肾髓质次级血管束内一些降直血管具有门静脉特点;直血管在乳头部肾盂上皮下形成致密血管丛,它是升、降直血管间的主要连接通道;内髓升、降直血管间还有毛细血管及少量血管襻连接。本文还讨论了上述结构特点的功能意义。     

小鼠肾远曲小管三维可视化研究

目的 肾远曲小管（DCT）是肾单位最后一段小管,其与相邻小管的分界及走行的毗邻关系是理解肾形态发生中集合管与肾单位连接方式,以及该段小管参与水盐代谢调节机制的重要结构基础。本实验在肾组织连续切片基础上,采用微细结构三维可视化技术,建立小鼠肾远曲小管的空间走行。 方法 C57/BL/6 J小鼠灌流固定后取肾,垂直于肾长轴切取组织块,树脂812包埋,从肾被膜到肾外髓外带获得2.5 μm厚连续切片720张,获取数字化显微镜图像并通过计算机程序进行配准,追踪来自3只小鼠共90个肾单位远曲小管,观察其空间走行并测量其长度。 结果 肾远曲小管起始于远端小管致密斑后40～180 μm处,上皮由矮柱状或立方陡然变为高柱状,细胞核靠近腔面,走行在皮质迷路其自身的肾小球周围,区域相对独立,末端向被膜方向逐渐移行为连接小管;此处上皮再次变矮,细胞核排列不局限在近腔面。浅层皮质肾单位的远曲小管在回旋返折最高处接触肾被膜1次。远曲小管长度为500～900 μm。 结论 远曲小管较短且盘曲走行,较少与其他小管交错,所以区域较小而独立,可能有助于该节段的吸收功能受激素的精准调节。     

带旋股外侧血管升支和横支骨瓣转位术的应用解剖

目的：为带旋股外侧血管升支和横支的骨瓣转位，治疗股骨干中下段骨不连的术式提供解剖学基础。方法：经４０侧灌注红色乳胶的成人标本上，对旋股外侧血管的升支、横支和降支的走行和分布进行了观测，并在标本上进行摹拟手术。结果：设计了带旋股外侧血管升支和横支的骨瓣，以降支为带转移到股骨干中下段的手术方法。结论：本研究证明了该方法治疗股骨干中下段骨不连的可行性，并有简便、易行和可靠的优点     

家兔坐骨神经初级传入纤维在脊髓内的定位投射—HRP跨越神经节追踪研究

向家兔坐骨神经的分支一胫神经、腓神经、比目鱼肌(腓肠肌)神经、腓肠皮神经分别注入HRP溶液,跨越神经节追踪了各该神经初级传入纤维在脊髓内的分布,得到了下列几点规律性认识。 1.来自皮肤的外感性传入纤维分布于后角浅层(Ⅰ—Ⅳ层),来自肌肉的Ia类粗纤维分布于后角深层及中间带外侧核区、前角。 2.外感性细纤维在后角Ⅱ、Ⅲ层有浓密的投射,各神经有特有的占位区。内脏初级传入纤维不向Ⅱ、Ⅲ层投射。 3.与痛党有关的Aδ、C纤维经Lissauer's束投射向后角Ⅰ、Ⅱ层,其它感觉的外感性纤维经后索分布于后角Ⅳ层并有一部分入Ⅲ层。 4.Ia类粗纤维经后索入灰质,首先在Ⅴ、Ⅵ层内侧部形成浓密的晶体形终末区并经Ⅵ层中央部向中间带外侧核区、前角运动核区(Ⅸ层)放散。粗纤维在后索内形成升、降支,向吻侧跨约10个节段逐节发出侧支终止在相当于Ⅴ、Ⅵ层内侧部处;向尾侧终止于骶、尾各节段的后连合核区。 5.进入脊髓的各类纤维中,止于Ⅰ、Ⅱ层的细纤维跨节段最少;止于Ⅳ层的外感性纤维向吻侧跨2—3节,向尾侧直达尾髓;Ia类粗纤维跨节段范围最大,升支可达T_9,降支直达尾髓。     

发生发育小鼠肾近端小管的三维可视化

目的 成年肾近端小管（PT）是急性肾小管病变最常累及同时也最易修复的节段,探讨基于三维可视化对发生发育期PT的形态发生进行时空性分析。 方法 取胚胎期（E）及生后（P）多时间点小鼠肾脏每组各3只,制备5 μm石蜡切片,Claudin-2免疫组织化学染色标记PT,体视学测量PT在肾皮质中体积密度;制备2.5 μm连续树脂切片并使之图像化,基于数字追踪和可视化软件展示PT的空间走行,同时测量其长度。 结果 P1小鼠PT在皮质中的体积密度明显大于胚胎期;随后经历了下降（P3、P5）、上升（P7）开始至稳定的成年水平（P28）;E14.5、E17.5和P5小管三维可视化显示,发生发育PT的长度、曲部的盘曲数随小管成熟逐渐增加,但低于成年PT;E14.5、E17.5 PT的基本空间走行与成年相似,而PT起始段的走行及PT直部在髓放线走行的毗邻关系则较成年差异较大;P5部分PT的走行接近成年PT。 结论 PT的发育,无论是皮质中的体积密度、长度、空间走行,与肾的整体发育一致,始于S小体期,贯穿于胚胎期并延续至生后,止于肾发育成熟（P28）。     

苏皖地区儿童随意尿THP的正常值调查

Tamm-Horsfall蛋白(Tamm-Horsfallprotein,THP)是一种大分子糖蛋白,主要来源于肾脏,THP合成于髓袢升支粗段及远曲小管上皮细胞内的高尔基体,分布在髓袢升支粗段及远曲小管上皮细胞表面。体内正常量的THP(无论是尿液还是血液)有赖于正常肾组织的存在。肾病患者的血、尿THP含量减     

脊髓前动脉的外科解剖学

本文报告10例成年尸体脊髓前动脉的外科解剖学的研究结果。目的为脊髓缺血性损害发生截瘫行血管重建提供解剖学资料。研究结果:前髓动脉外径平均0.6mm,升支外径0.5mm;降支外径0.5mm。动脉干长度:颈段平均1.2cm:上胸段平均2.3cm。大前髓动脉外径较大,平均0.9mm;升支外径平均0.5mm;降支外径平均1.0mm。此动脉长度平均2.6cm。     

Histogenesis of the loop of Henle in the rat kidney

Summary The epithelial differentiation of the loop of Henle was investigated in the kidneys of Wistar rats between embryonic day 15 and postnatal day 30. Three stages can be distinguished in the development of the loop of Henle: (1) the primitive loop, (2) the immature loop and (3) the mature loop. The primitive loop of Henle is composed of thick undifferentiated tubule epithelium and is divided into a strongly basophilic proximal tubule anlage that stains dark in the semithin section, and a weakly basophilic, light-staining distal tubule anlage. The two anlages are separated by a cytologically sharp boundary located in the descending limb just before the bend of the loop. The immature loop of Henle is present when differentiation of the tubule epithelium begins. The shorter initial portion of the proximal tubule anlage develops into proximal straight tubule epithelium with brush border, brush border enzymes and lysosomal enzymes, while the longer, more distal portion of the proximal tubule anlage develops into thin undifferentiated epithelium that is a transitory feature of the immature loop stage. The primitive epithelium of the distal tubule anlage develops into distal straight tubule epithelium. The cytologically sharp boundary of the thin undifferentiated epithelium and distal tubule epithelium is located just before the bend of the loop. The loop of Henle matures as the thin undifferentiated epithelium in the medullary ray and outer stripe of the outer medulla becomes transformed into proximal straight tubule epithelium. At the point where this descending differentiation ends, the borderline of the inner and outer stripe of the outer medulla arises. The thin undifferentiated epithelium in the inner stripe and the inner medulla differentiates into the thin epithelium of the descending limb of Henle's loop. In the bend and ascending limb of long loops, the thick distal tubule epithelium is trans-formed by an ascending autophagous process into the thin epithelium of the ascending limb of Henle. The termination of this process marks the borderline between the inner and outer medulla. The thin descending and thin ascending limb of Henle arise from 2 different anlages; between them lies the histogenetic boundary of the proximal and distal renal tubule.Supported by the Deutsche Forschungsgemeinschaft (SFB 105)     

The ultrastructure of the thin limbs of henle in kidneys of the desert heteromyid (Perognathus penicillatus)

The thin limbs of both long- and short-looped nephrons in Perognathus kidneys were studied with transmission and scanning electron microscopy. The superficial nephrons have a short thin limb located in the vascular bundles of the outer medulla and are characterized by a simple, low-lying epithelium (0.4 ± 0.1 μ thickness). In contrast, the first descending part of the thin limb of the majority of midcortical and juxtamedullary nephrons has a relatively thick epithelium (1.7 ± 0.6 μ in thickness) with marked lateral and basal interdigitation and a dense surface covering of microvilli. The remaining part of the long descending thin limb is relatively simple with a low-lying epithelium (0.6 ± 0.1 μ in thickness), decorated on its surface by sparse microplicae. The bend of the loop and the ascending limb are covered by a very simple low-lying epithelium (0.6 ± 0.2 μ in thickness) with relatively little surface modification. The extreme urine-concentrating ability of Perognathus does not appear to be due to the development of a unique thin loop epithelium but rather to the extensive length of the inner and outer medulla.     

Effect of increased distal sodium delivery on organic osmolytes and cell electrolytes in the renal outer medulla

Sodium absorption in distal tubule segments was stimulated by increasing the distal delivery via infusion of hypertonic saline. In these animals, and in control rats, electrolyte concentrations in thick ascending limb cells, light and dark cells of the collecting duct in the outer and inner stripe of the outer medulla and in cells of the proximal straight tubule (outer stripe only) were studied. The measurements were performed by electron microprobe analysis of freeze-dried cryosections of the outer medulla. In addition, organic osmolytes (glycerophosphorylcholine, betaine and myo-inositol) were measured by high performance liquid chromatography in cortex and outer medulla. Augmented delivery of sodium chloride to the distal tubule was associated with increased sodium concentrations of thick ascending limb cells both in the outer and inner stripe and of medullary collecting duct light and dark cells in the outer stripe. While the sum of organic osmolyte concentrations was 28% higher in the outer medulla of the salt-loaded animals compared with controls, this value was unchanged in the renal cortex. These findings indicate that the primary event underlying stimulation of sodium absorption along the thick ascending limb during increased distal sodium delivery is enhanced entry of sodium across the apical cell membrane. This would be expected to lead to higher cell sodium concentrations and stimulation of basolateral active Na-K-exchange. The enhanced transport activity of outer medullary tubules may be associated with increased interstitial tonicities and intracellular retention of organic osmolytes.     

The structural organization of the kidney of the desert rodent Psammomys obesus.

The architecture of the desert rodent Psammomys obesus has been studied by means of standard histologic procedures and by single nephron injections. As other rodent kidneys (rat, mouse), the Psammomys kidney consists of two types of nephrons, 66% short looped and 34% long looped nephrons. The cortex is composed of 4 to 5 layers of glomeruli, which lie closely put together, the glomeruli often touch each other. The superficial and the midcortical glomeruli give rise to short looped neophrons, the juxtamedullary to long looped nephrons. In the strongly developed medulla the inner stripe shows the most striking pattern. It consists of two distinct compartments, that of the giant vascular bundles and that of the interbundle regions. The giant vascular bundles consist of about 8 to 14% arterial vasa recta and 39 to 47% venous vasa recta; furthermore they include the thin descending limbs of the short loops of Henle which amount to 44 to 51% of the bundle structures. The tubules of the interbundle regions surround the bundles in a regular pattern. The inner zone is almost completely surrounded by the renal pelvis; the long broad papilla protrudes into the ureter. The thin descending limbs of short looped nephrons traverse the inner stripe inside the giant vascular bundles. Leaving the bundles they turn back within the inner stripe; their ascending limbs lie in the interbundle region. Both limbs of the long loops of Henle run in the interbundle region, together with the ascending limbs of the short loops and the collecting ducts. The long loops penetrate deeply the inner zone. Many bends are found near the tip of the papilla. The renal pelvis has a very specialized form. It penetrates the inner stripe with many complexely shaped extensions, which surround the giant vascular bundles. Large parts of the bundles with their thin walled structures are thus separated from the pelvic urine only by a single layer of cuboidal epithelium. The possible functional importance of the described specializations of the Psammomys kidney (giant vascular bundles, large inner zone, special shape of the renal pelvis) for the urine concentrating and urea recyclng mechanisms is discussed.     

Urine concentrating mechanism in the inner medulla of the mammalian kidney: role of three-dimensional architecture

The urine concentrating mechanism in the mammalian renal inner medulla (IM) is not understood, although it is generally considered to involve countercurrent flows in tubules and blood vessels. A possible role for the three-dimensional relationships of these tubules and vessels in the concentrating process is suggested by recent reconstructions from serial sections labelled with antibodies to tubular and vascular proteins and mathematical models based on these studies. The reconstructions revealed that the lower 60% of each descending thin limb (DTL) of Henle's loops lacks water channels (aquaporin-1) and osmotic water permeability and ascending thin limbs (ATLs) begin with a prebend segment of constant length. In the outer zone of the IM (i) clusters of coalescing collecting ducts (CDs) form organizing motif for loops of Henle and vasa recta; (ii) DTLs and descending vasa recta (DVR) are arrayed outside CD clusters, whereas ATLs and ascending vasa recta (AVR) are uniformly distributed inside and outside clusters; (iii) within CD clusters, interstitial nodal spaces are formed by a CD on one side, AVR on two sides, and an ATL on the fourth side. These spaces may function as mixing chambers for urea from CDs and NaCl from ATLs. In the inner zone of the IM, cluster organization disappears and half of Henle's loops have broad lateral bends wrapped around terminal CDs. Mathematical models based on these findings and involving solute mixing in the interstitial spaces can produce urine slightly more concentrated than that of a moderately antidiuretic rat but no higher.     

Morphologic and functional evidence for oxygen deficiency in the isolated perfused rat kidney

Morphologic and functional studies were undertaken in the isolated rat kidney, perfused with an albumin-Krebs-Henseleit solution, to which 5% human erythrocytes and/or various amino acids had been added. Perfused only with the albumin-Krebs-Henseleit solution, the kidneys displayed a characteristic pattern of cell necrosis after 2 hours of perfusion, which was confined to the interbundle region of the outer medulla and was not evident in either the cortex or the inner medulla. In the outer stripe only those proximal straight tubules (P3 segments) farthest from the vascular bundles were damaged. In the inner stripe only those thick ascending loops of Henle at the periphery of the vascular bundles escaped damage; all thick ascending loops of Henle lying farthest from the bundles were severely damaged. The number of damaged tubules increased toward the border to the inner medulla. Necroses in both segments, P3 and thick ascending loops of Henle, could be prevented by perfusion with the erythrocyte-albumin-Krebs-Henseleit solution but not by the addition of glutathione, in the absence of erythrocytes. Perfusion with the erythrocyte medium also significantly improved glomerular filtration rate and sodium and glucose reabsorption. It is concluded that, in the isolated, erythrocyte-free perfused kidney, the oxygen content of the "arterial" vasa recta in the vascular bundles is only sufficient to supply the tubules in the immediate surroundings. Countercurrent exchange in the vascular bundles between arterial and "venous" vasa recta progressively lowers the arterial oxygen content as the inner stripe of the outer medulla is approached and with it the number of tubules receiving an adequate oxygen supply.     

Blood supply and drainage of the outer medulla of the rat kidney: scanning electron microscopy of microvascular casts

Blood supply and drainage of the outer medulla of the rat kidney were studied by scanning electron microscopy of vascular casts, using both arterial (n = 10) and venous (n = 10) injections of resin. Both outer and inner stripes of the outer medulla were supplied through different arterial capillary networks arising from efferent arterioles and arterial (descending) vasa recta. In contrast to previous studies using silicone rubber and light microscopy, a rich arterial capillary network supplying the outer stripe was demonstrated. Capillaries in the outer stripe and outer part of the inner stripe drained into venous vasa recta between vascular bundles, while capillaries in the inner part of the inner stripe drained into venous vasa recta within the bundles. The results indicate that each zone in the outer medulla is supplied through separate capillary networks. The demonstration of a rich capillary network in the outer stripe of the outer medulla suggests that the predilection of this zone for tubular necrosis with ischemic or toxic injury is not related to a sparse capillary blood supply.     

Urea handling by the renal countercurrent system: Insights from computer simulation

Summary The renal handling of urea has been investigated with the aid of a computer model of the countercurrent system in which active electrolyte reabsorption occurs along the entire ascending limb of Henle's loop. In this model, summarized in Fig. 9, the buildup of a corticopapillary gradient for urea is optimized if there isnet addition of urea to loops of Henle only in the outer medulla. This added urea remains within the tubular system until it is reabsorbed from collecting ducts in the inner medulla. Thus, a net transfer of urea from outer to inner medulla is accomplished (via distal tubule and cortical collecting duct). There is nonet addition of urea to loops of Henle within the inner medulla; in this region, the loops act simply as countercurrent exchangers for urea. Computer simulation of systematic variation in the urea permeabilities of each nephron segment shows that interference with any element of the above schema results in impairment of the medullary accumulation of urea relative to plasma. Simulation of varying rates of urinary urea excretion demonstrates that this model can account for the ability of the kidney to excrete substantial amounts of urea without an accompanying osmotic loss of water. The major insight gained from this study is that net addition of urea to loops of Henle in the outer medulla greatly enhances the medullary accumulation of urea, whereas, net addition of urea to loops within the inner medulla tends to defeat such accumulation and hence the urinary concentrating process. This general principle applies also to an alternate model of the countercurrent system, in which electrolyte reabsorption from thin ascending limbs of Henle is passive.