ABSTRACT
Objective The use of in vivo cryotechnique (IVCT) in combination with electrocardiograph (ECG) to study cardiac microcirculation under different hemodynamic conditions in living mouse.Methods Living mouse heart monitored by electrocardiograph was suffered from IVCT and freezing substitution under normal blood flow,myocardial ischemia or cardiac arrest conditions.Hematoxylin eosin (HE)staining,Schiff's staining and immunofluorescence staining for serum albumin,immunoglobulin were utilized on continuous paraffin sections,respectively.Confocal microscopy and statistical analyses were used.Results Comparing with normal hemodynamics,microvascular red cell volume reduction,morphology changed,myocardial cell glycogen loss,serum albumin ectopic distribution to myocardial cytoplasm,T tubular network failure and spacing width were happened in myocardial iscbemia condition; different shapes of red blood cells,myocardial cells glycogen deficiency,T tubular network failure and interval narrowing were found under cardiac arrest conditions.Conclusions Cardiac microcirculation,pathological changes of myocyte and its surrounding microenviroument in living mouse heart can be immediately captured in situ by the application of IVCT and ECG.
ABSTRACT
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.
ABSTRACT
Objective To investigate the expression of endocytic receptor megalin and cubilinin in the developing mouse kidneys, and the correlation between the expression and the development of the renal tubules. Methods Expression of megalin and cubilin in developing mouse kidneys was examined at different embryonic days (E) using immunohistochemistry. Meanwhile, the ultrastructure of developing proximal tubules related to endocytosis was observed at transimission electron microscope level. Results At E9.5, megalin and cubilin were co-expressed in apical plasma membrane of the mesonephric ducts and mesonephric tubules. From E11 to E18, in the metanephros, the expression of both receptors were seen at the free surface and apical plasma of uretic bud, but weakly in all renal tubules of S shaped body at early differentiatial stage. With the mature of proximal tubule development, they were both confined to the brush border and the apical plasma of the proximal tubules in juxtamedullary cortex.Conclusion The endocytic receptors, megalin and cubilin are expressed in apical part of nearly all renal tubule epithelia in early development, and confined to free surface of mature proximal tubules, suggesting that with the mature of proximal tubules, the two receptors are generally involved in collaborating to facilitate, the reabsorption of ultrafiltration.