2005 Abstracts: Mouse Liver Anatomy From a Microsurgical Point of View
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Mouse Liver Anatomy From a Microsurgical Point of View
Daniel Inderbitzin, Daniel Sidler, Peter Studer, Beat Gloor, University Hospital Bern, Bern, Bern, Switzerland; Valentin Djonov, University Bern, Bern, Bern, Switzerland; Daniel Candinas, University Hospital Bern, Bern, Bern, Switzerland
Background: During the development of different mouse liver resection models for hepatic regeneration research a significant lack of basic anatomical data of the mouse liver became obvious. Relative liver weight and individual lobe size were unknown. After resection of the median lobe (M) a necrosis of the remaining left lobe (L) was occasionally encountered, and furthermore an impaired regenerative response of the caudate lobe (C) was detected. In order to elucidate the observations made, the following basic anatomical studies of the mouse liver were undertaken.
Methods: In male Balb/c mice (n=32, 18–26g) liver mass and individual liver lobe weights were determined. The hepatic vascular system was studied by corrosion casts (n=8). Hematoxylin/Eosin stainings of paraffin embedded liver lobes (n=15) were used to study the micro-anatomical correlation of liver vessels and hepatic parenchyma. For scanning electron microscopy (SEM) the mouse liver was perfused with a mercox solution. Casts were sputtered with gold (10 nm) and examined in a Philips XL 30 FEG scanning electron microscope. Results: Liver weight (LW) was increasing up to a mouse body weight (BW) of 23.6g and decreasing thereafter (LW (g) = -0.0022*BW [g]2 + 0.1025*BW [g]). Relative lobe specific liver mass was: L = 34.4±2.1% (Standard deviation); M = 26.2±1.9%; Right superior (RS) = 16.6±1.4; Right inferior (RI) = 14.7±1.4%; C = 8.1±1.0%. Vascular corrosion casts demonstrated detailed three-dimensional anatomy and a single pedicle in the RS, RI, and C lobes. A common pedicle was seen for M and L lobes in 3/8 cases. In histological sections vascular density, total vascular luminal area and calculated volumes of liver lobules were not different between liver lobes. SEM showed remarkably smaller hepatic lobules in the C lobe (when compared with RS) with significantly increased vascular density. Conclusions: Relative mouse liver mass varies considerably with age and weight. A common vascular pedicle of the M and L lobe explains the inhomogeneous perfusion observed after some isolated M resections. This resection is therefore not recommendable in the mouse. A higher vascular density in the C lobe with smaller hepatic lobules as seen in SEM might explain the observed impaired hepatic regenerative capacity. Our anatomical data underline the importance of the careful selection of the appropriate microsurgical model when studying the mechanism of liver regeneration and repair.
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