title: Nephron morphometry in mice and rats using tomographic microscopy.
abstract: The aim was to quantify the glomerular capillary surface area, the segmental tubular radius, length, and area of single nephrons in mouse and rat kidneys. Multiple 2.5-µm-thick serial Epon sections were obtained from three mouse and three rat kidneys for three-dimensional reconstruction of the nephron tubules. Micrographs were aligned for each kidney, and 359 nephrons were traced and their segments localized. Thirty mouse and thirty rat nephrons were selected for further investigation. The luminal radius of each segment was determined by two methods. The luminal surface area was estimated from the radius and length of each segment. High-resolution micrographs were recorded for five rat glomeruli, and the capillary surface area determined. The capillary volume and surface area were corrected for glomerular shrinkage. A positive correlation was found between glomerular capillary area and proximal tubule area. The thickest part of the nephron, i.e., the proximal tubule, was followed by the thinnest part of the nephron, i.e., the descending thin limb, and the diameters of the seven identified nephron segments share the same rank in the two species. The radius and length measurements from mouse and rat nephrons generally share the same pattern; rat tubular radius-to-mouse tubular radius ratio ≈ 1.47, and rat tubular length-to-mouse tubular length ratio ≈ 2.29, suggesting relatively longer tubules in the rat. The detailed tables of mouse and rat glomerular capillary area and segmental radius, length, and area values may be used to enhance understanding of the associated physiology, including existing steady-state models of the urine-concentrating mechanism.
authors.affiliation: Biomedical Engineering Research Group in the School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Robyn F R
authors.initials: RF
authors.lastname: Letts
authors.affiliation: Department of Histology and Embryology, China Medical University, Shenyang, People's Republic of China; and.
authors.forename: Xiao-Yue
authors.initials: XY
authors.lastname: Zhai
authors.affiliation: Biomedical Engineering Research Group in the School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Charita
authors.initials: C
authors.lastname: Bhikha
authors.affiliation: Department of Biomedicine-Anatomy, Aarhus University, Aarhus, Denmark.
authors.forename: Birgitte L
authors.initials: BL
authors.lastname: Grann
authors.affiliation: Department of Biomedicine-Anatomy, Aarhus University, Aarhus, Denmark.
authors.forename: Nicklas B
authors.initials: NB
authors.lastname: Blom
authors.affiliation: Department of Biomedicine-Anatomy, Aarhus University, Aarhus, Denmark.
authors.forename: Jesper Skovhus
authors.initials: JS
authors.lastname: Thomsen
authors.affiliation: Biomedical Engineering Research Group in the School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: David M
authors.initials: DM
authors.lastname: Rubin
authors.affiliation: Department of Biomedicine-Anatomy, Aarhus University, Aarhus, Denmark.
authors.forename: Erik I
authors.initials: EI
authors.lastname: Christensen
authors.affiliation: Department of Histology and Embryology, China Medical University, Shenyang, People's Republic of China; and.|Department of Biomedicine-Anatomy, Aarhus University, Aarhus, Denmark.
authors.forename: Arne
authors.identifier: 0000-0002-2160-591X
authors.initials: A
authors.lastname: Andreasen
mesh_terms: D000818:Animals; D007671:Kidney Concentrating Ability / Q000502:physiology; D007678:Kidney Glomerulus / Q000473:pathology*; D007687:Kidney Tubules, Proximal / Q000473:pathology*; D008297:Male; D008810:Mice, Inbred C57BL; D008853:Microscopy; D009399:Nephrons / Q000473:pathology*; D017208:Rats, Wistar; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: digital tracing; glomerular capillary area; rat and mouse kidney morphology; three-dimensional structural analysis