小鼠长髓襻肾单位在髓质的分布

目的 肾髓质渗透梯度的形成与髓襻走行及转运功能关系密切,本研究拟建立长髓袢肾单位在髓质的走行规律。方法C57BL6/J小鼠3只,灌流固定后取肾组织块,树脂812包埋,垂直肾长轴连续半薄切片,从肾被膜到内髓,共得到2 000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26条长髓襻肾单位。结果 长髓襻肾单位来自中层和近髓质区的皮质,其髓襻襻曲分布在内髓不同水平,最深的可达肾乳头。通过数字追踪发现,在外髓内带外侧区,髓襻降支细段起始部高度盘曲走行,其盘曲部分的长度是其直线距离的2倍。在盘曲走行中,与同源的髓襻升支粗段间隔排列。最长的长髓襻升支粗段走行在外髓内带的血管丛。在外髓内带的内侧区,髓襻降支细段与髓襻升支粗段紧密相邻,直行进入内髓。结论 降支细段在外髓内带高度盘曲走行,在增加了这一节段长度的同时,也增加了这一节段的转运功能,提示此结构特征对该区域的渗透梯度形成可能产生重要影响。     

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。     

Na-K-2Cl共同转运蛋白(NKCC2)基因研究进展

Na-K-2Cl共同转运体在维持肾小管髓袢升支粗段对NaCl 的重吸收,机体容量控制方面起重要作用,NKCC2基因突变可使其编码蛋白质结构、功能改变, 使体内血压调节的稳态发生变化。     

肾脏微循环与肾脏疾病

<正> 肾脏微循环在形态与动态方面,都与肾脏的功能相适应,肾脏病变时,其微循环也发生相应的变化。一、肾脏微循环的结构组成与特点肾脏的基本功能单位与结构单位是肾单位。肾脏的微循环主要是指发生在肾单位的血液循环。人类每只肾脏的肾单位数在100万以上,其中皮质肾单位占绝大多数,他们的袢枝短,主要司滤过功能,髓旁肾单位则有一个长袢伸到髓质的内部,在尿液的浓缩与稀释过程中起重要作用。入球小动脉是肾单位供血的进路,它反复分支形成毛细血管丛后再汇集成出球小动脉。出球小动脉形成球后毛细血管网,分布于肾小管曲部的四周。髓旁肾单位的出球小动脉还发出直小动脉进入髓质。球后毛细血管网汇合流入小叶间静     

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。     

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。     

mTOR复合物在糖尿病肾病小鼠肾组织中的不同分布和表达

目的探讨哺乳动物雷帕霉素靶分子复合物(mTORC)在糖尿病肾病(DN)小鼠肾组织中的分布、表达。方法 14只C57BL/6小鼠随机分成对照组和DN组,每组各7只。DN组小鼠予以链脲菌素腹腔注射建立小鼠DN模型,采用生化技术检测小鼠血、尿肌酐以及白蛋白水平,组织学染色检测肾脏病理变化,免疫荧光以及免疫印迹技术检测肾组织中mTOR、mTOR第2448位丝氨酸磷酸化修饰后mTOR(p-mTOR)、mTORC1(Raptor)、mTORC2(Rictor)以及mTOR信号通路下游的效应蛋白磷酸化S6K1(p-S6K1)的分布和表达。结果 DN组小鼠血糖、尿白蛋白/肌酐比值明显增加(P0.01),肾小球明显增大(P0.05)。mTOR、Raptor以及Rictor在正常以及DN小鼠肾皮质和髓质中均有表达,主要表达在肾小球系膜区、毛细血管袢、皮质近曲小管以及外髓和内髓集合管上皮细胞中。其中正常小鼠内髓肾组织中未见p-S6K1表达,正常以及DN小鼠肾小球中未见p-mTOR表达。免疫印迹检测表明,DN小鼠肾组织中mTOR、p-mTOR、Raptor、Rictor以及p-S6K1均明显上升(P0.05)。结论 mTORC广泛分布于小鼠肾组织且参与DN的发生发展,但mTOR第2448位丝氨酸磷酸化并不直接参与高血糖介导的肾小球损伤。     

中华鳖肾组织微细结构的性别差异

目的 探讨雌、雄中华鳖肾组织的微细结构特征及意义。方法 利用甲苯胺蓝半薄切片和透射电镜超薄切片技术,研究20只雌、雄中华鳖肾脏组织结构。结果 雌、雄中华鳖肾脏肾小管的近端小管和中间段上皮细胞结构存在一定差异,表现在雄性的近端小管立方上皮细胞之间含有侧细胞间隙,基底膜与基膜之间存在基底细胞间隙。侧细胞间隙内分布有由质膜形成的指状突起,细胞基底间隙中分布由基底膜形成的基底迷路。雌性近端小管立方上皮细胞间无侧细胞间隙和基底间隙。雌、雄鳖的中间段上皮细胞也表现出与近端小管立方上皮细胞相似的形态差异,即雄性肾小管的中间段立方上皮细胞间存在侧细胞间隙和基底间隙,间隙内分布有细长的指状突起,而在雌性肾小管的中间段上皮中无侧细胞间隙和基底间隙。雄性中华鳖近端小管上皮细胞有3种：主细胞、秃头细胞和基底细胞;与雄性不同,雌性的近端小管上皮仅有亮、暗两种上皮细胞。结论 雌、雄中华鳖肾脏近端小管和中间段的上皮组织结构存在性别差异。侧细胞间隙和基底间隙仅存在于雄性近端小管和中间段上皮细胞之间,上皮组织细胞之间的侧面间隙与细胞基底间隙应与物质运输有关,提示雄性近端小管的尿液重吸收能力和中间段上皮的尿液浓缩能力可能较雌性的强。     

人与狗迷走/交感干的比较解剖及其喉上神经外支纤维成分

目的　对人与狗的颈段迷走/交感干进行比较解剖,并鉴定狗的喉上神经外支的纤维成分。方法 随机解剖经福尔马林固定的成年人尸体颈部（n=50）及狗的颈部（n=10）,暴露其颈交感干与喉上神经及其外支间的交通;并取狗的喉上神经外支,甲醛固定,明胶包埋,恒冷切片后用Karnovsky AchE组化方法染色并观察。 结果 狗的迷走神经结状神经节与颈上神经节完全或部分融合,迷走神经干与交感神经干完全或部分融合为迷走-交感干;而人的结状神经节与颈上神经节互相分离;颈上神经节与喉上神经及其分支之间存在交通,其中颈上神经节与喉上神经外支相交通者占86%。AchE染色显示：狗的喉上神经外支含AchE阳性有髓神经纤维、AchE阴性有髓神经纤维和AchE阳性无髓神经纤维。 结论 喉上神经外支呈袢状,而非干式,含躯体运动、交感神经节后及躯体感觉纤维,因此喉上神经外支为一混合神经。     

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.     

The ultrastructure of the nephrons of the desert rodent (Psammomys obesus) kidney II. Thin limbs of henle of long-looped nephrons

Long nephrons are derived from juxtamedullary glomeruli. In their descent through the outer medulla toward the inner medulla, the thin descending limbs (TDLs) of long loops of Henle are consistently excluded from the vascular bundles and occupy the interbundle region. The outer medullary segment of long TDLs (Type II epithelium) is elaborately developed with numerous cellular interdigitations. microvilli, and a cytoplasm well equipped with numerous organelles. The inner medullary segment of these long TDLs is characterized by yet another epithelium that is markedly reduced from its Type II predecessor and is designated as Type III epithelium. It is a very low, flattened epithelium with few cytoplasmic details. In a cross section of the inner medullary TDL, the Type III epithelium appears poorly interdigitated, with only two to four cell processes and their junctional complexes. Shortly before the bend of a long loop of Henle, the epithelium is again altered to one that is well-interdigitated and better equipped with cytoplasmic organelles (Type IV epithelium). It persists through the actual bend of the loop and throughout the entire thin ascending limb (TAL), until the latter's transition to the distal tubule at the level of the inner/outer medullary border. We conclude that the Type II epithelium of the outer medullary segments of long TDLs in Psammomys is suitably constructed for involvement in energized transport of solutes. The possibility for a similar role in the Type IV epithelium of the bends and TALs is not excluded by our data. However, the Type III epithelium of the inner medullary segments of long TDLs is most suitably constructed for the concentration of its luminal fluids via water extraction. A comparison between these epithelial types and their permeabilities in various species is presented.     

Postnatal development of the interstitial tissue of the rat kidney

Summary To study the ontogenetic development of the interstitial tissue of the kidney, rats were investigated 1, 3, 7, 14, 21 and 28 days after birth. Kidneys perfusionfixed with glutaraldehyde were studied with light- and electron microscopy. Cryostate sections from kidneys immediately frozen in liquid nitrogen were studied with respect to the expression of MHC class II antigen using the monoclonal antibody OX6. The interstitial space of both the renal cortex and the outer and inner medulla was prominent during the first days postnatally. The relative interstitital volume of the cortex and outer part of the medulla then decreased in conjunction with the outgrowth and maturation of the superficial nephrons while the inner medullary interstitium remained wide. During the first postnatal days, the abundant interstitial cells of the cortex were connected via cytoplasmic processes to form a loose network which later became less well defined. The lipid-laden interstitial cells of the inner medulla showed essentially the same ultrastructure in the newborn as in the adult animal. Strong expression of class II antigen first appeared on epithelial cells of the thick ascending limb of Henle’s loop about 7 days postnatally, and became weak at 28 days. From 21 days, a weak staining of the proximal tubules was also observed. While interstitial cells in the inner medulla were always negative, cortical and outer medullary interstitial cells became strongly positive for class II antigen from day 21 post partum.     

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.     

Dynamics of hyaluronan, CD44, and inflammatory cells in the rat kidney after ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury in the kidney involves hemodynamic and cellular dysfunctions as well as leukocyte infiltration. Functional recovery occurs via cell proliferation and/or migration. To determine the roles of hyaluronan (HA) and its main receptor CD44 in renal postischemic processes, we compared their localization and expression with that of neutrophils, macrophages, and PCNA-positive (regenerative) cells as characterized by immunohistochemistry, up to 28 days after I/R in uninephrectomized rats. Observations covered all kidney zones, i.e. cortex (C), outer and inner stripes of outer medulla (OSOM, ISOM), and inner medulla (IM). In controls, HA was localized to the interstitium of IM and ISOM, and CD44 was mostly present on the basolateral membranes of collecting ducts in ISOM, the thin descending limb of Henle's loop and macula densa cells. After I/R, HA and CD44 staining appeared in C and OSOM at 12 h and persisted throughout the regenerative period, i.e. until day 7. Thereafter, they regressed but remained associated with remodeling areas. CD44 expression was found de novo on the apical pole of regenerating, not fully differentiated tubular cells and on some interstitial cells. It was prominent on all infiltrating neutrophils, as soon as 2 h post-I/R, and on 30% of the macrophages, including those in late HA-rich inflammatory granulomas. CD44 is probably involved in early leukocyte infiltration, in tubular regeneration, and in macrophage activity, while HA modifies the physico-chemical environment of interstitial and migrating cells. Based on its presence in remodeling areas, the HA-CD44 pair may be implicated in persistent postichemic inflammation as observed in chronic allograft nephropathy.     

The pelvic epithelium of the rat kidney: A scanning and transmission electron microscopic study

The renal pelvis of the rat is characterized by extensions called specialized fornices that penetrate into the outer zone of the outer medulla (a type II as classified by Pfeiffer, 1968, 1970). The renal pelvic epithelium, therefore, covers areas of the kidney from the inner medulla, the inner and outer stripe of the outer medulla, and the cortex. The renal pelves of seven rats were studied by transmission and scanning electron microscopy. The transitional epithelium on the nonparenchymal surface of the pelvis was three to four cell layers thick (zone 0–1). This epithelium became thinner where it covered the renal cortex (zone 1–2) or the outer medulla. Although the apical cells of the epithelium retained the asymmetric luminal unit-membrane plaques, the number of cytoplasmic fusiform vesicles decreased as one studied the epithelium progressing over the zones from cortex toward papilla. Scanning electron microscopy demonstrated a small number of surface cells of a different morphology that were characterized by apical microvilli. The number of these microvillous lining cells increased as the epithelium covering the outer (zone 2–3) and inner (zone 3–4) stripe regions of the outer medulla was viewed, until the inner medulla was entirely covered by this cell type. In a reciprocal manner, the cells with the asymmetric apical plaques decreased in numbers and in their morphologic specialization in each successive region. The epithelium surrounding the inner medulla (zone 6–7) was completely devoid of this transitional cell type. Judging from the morphologic characteristics of the epithelia, one could surmise that little exchange of urea, water, and salts would occur with the extrarenal connective tissue or the cortical parenchyma. Recycling of urea might become more important physiologically with the outer stripe parenchyma, and even more so with the increased surfaces of the inner stripe parenchyma that lined the secondary pyramid, as well as with the epithelium lining the inner medulla.     

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.