Fig 1.
Pressure-controlled embalming of pig kidneys.
Thiel embalming fluid is pumped in the renal artery, and a mixture of blood and/or embalming fluid eventually leaves the kidney through the renal vein.
Fig 2.
Stepwise illustration of both experiments.
(A) Pressure-controlled Thiel embalming followed by immersion in a concentrated salt solution. (B) Reperfusion of Thiel embalmed and dehydrated kidneys with either PP or diluted PEG.
Fig 3.
Renal spreading of Thiel embalming fluid.
(A) Planar CT image shows three areas of filling (contrast): bright, the main arterial and venous system and the poles-medial border of the kidney; intermediate grey, centrally distributed areas; and darker grey, areas at the core and kidney surface. Two oblique white lines represent virtual slicing through the upper and lower mid-central part of the kidney. (B) Three-dimensional representation of the same kidney; red, main arterial and venous system and one of the poles-medial border areas; transparent purple, centrally distributed areas of the kidney showing intermediate contrast filling; and white polylines, inner core areas (four cone-like structures, calices) and surface of the kidney showing the least contrast filling.
Fig 4.
Weight and volume changes in embalmed and dehydrated kidneys.
(A) A weight gain occurs after embalming (P = 0.005), and a weight loss (P < 0.001) occurs following the subsequent dehydration, respectively. The combination of these two procedures results in a significant weight reduction (P = 0.007). (B) Swelling occurs after embalming (P = 0.007), and volume loss occurs following the subsequent immersion in a concentrated salt solution (P < 0.001). The combination of both procedures results in a significant volume reduction (P = 0.003).
Fig 5.
Effect of embalming and dehydration on renal status.
(A) Fresh pig kidney. (B) Thiel embalmed pig kidney. Note the swelling and zonal discolouring due to the embalming. (C) Thiel embalmed and dehydrated pig kidney. The organ is shrunken and discoloured, but remains pliable.
Fig 6.
Percent weight and volume change during embalming, dehydration and reperfusion of pig kidneys.
(A) Embalming and subsequent dehydration cause a significant weight gain (P < 0.0001) and loss (P < 0.0001), respectively. Persistent weight gain is observed during initial reperfusion with diluted PEG or PP (both P = 0.005), whereas weight gain is not present after more than 60 minutes of reperfusion with PP (P = 0.26). In contrast, ongoing weight gain (P = 0.005) is noted during reperfusion for more than 60 minutes with diluted PEG. (B) Embalming and subsequent dehydration cause a significant volume increase (P < 0.0001) and loss (P < 0.0001), respectively. In the beginning, a continuous volume increase is noted in the case of reperfusion with diluted PEG (P = 0.005) as well as PP (P = 0.007). No further increase is observed after more than 60 minutes of reperfusion with PP (P = 0.79), whereas an ongoing volume gain is present in the case of diluted PEG (P = 0.032). Weight/volume after embalming = green; after dehydration = brown; at the start of reperfusion = purple; at first venous drainage = yellow; after 60 minutes of reperfusion = red; after 120 minutes of reperfusion = blue.
Fig 7.
Intra-arterial pressure during renal reperfusion.
PP generates lower pressures than diluted PEG (P < 0.05). Ongoing pressure decrease is observed during more than 60 minutes of reperfusion with PP (P = 0.032), whereas the pressure increases further (P < 0.0001) when diluted PEG is used. The generated pressures remain, however, lower than the mean arterial blood pressures in adult pigs. The error bars with 95% confidence intervals are shown.
Fig 8.
Contrast-enhanced reperfusion of Thiel embalmed and dehydrated pig kidneys with PP and diluted PEG.
(A) Planar CT image shows two distinct areas of filling: the arterial and venous system (bright) demonstrating that PP recruits the major renal vessels and the renal tissue (dark grey). ra, renal artery; sa, segmental artery; la, lobar artery; ila, interlobar artery; aa, arcuate artery; illa, interlobular artery; iv, interlobar vein; sv, segmental vein. (B) Three-dimensional representation of the same kidney; red, arterial and venous system; transparent blue-grey, renal tissue showing less contrast. (C) Planar CT image illustrates one uniform area of filling: the arterial and venous system together with the renal tissue (light grey) and centrally a darker area (dark grey) representing the renal calices. (D) Three-dimensional representation of the same kidney. The renal tissue is transparent purple, and the segmental vessels are highlighted in red for illustration purposes. The central white polylined structure depicts the renal calices. (E) The white horizontal line represents the cross-sectional slice through the mid-central part of the kidney containing renal tissue, segmental vessels and the renal calices. (F) Top view of the caudal part following the virtual slicing illustrated in E. Transparent purple, renal tissue; the segmental vessels are highlighted in red and have the same contrast as the renal tissue; white polylines border the calices, which are not filled or are less filled by the contrast fluid. (G) Cross-section through frozen Thiel embalmed pig kidney reperfused with PP. Red PP is present in the major renal vessels. (H) Cross-section through frozen Thiel embalmed pig kidney reperfused with diluted PEG. Blue diluted PEG diffusely stains the sectioned renal surface.
Fig 9.
Morphological changes of renal cortex during embalming, dehydration and vascular reperfusion.
Pig cadaver kidneys. A-E: Hematoxylin and Eosin staining (magnification: x 400). (A) Fresh renal cortex. Glomerular vessels (black arrow) and peritubular capillaries (arrowhead) contain red blood cells. (B) Thiel embalmed renal cortex. Cloudy cell swelling causes rupture of cells (black arrows) and glomerular disintegration. Embalming fluid accumulates in the interstitium (arrowhead) and Bowman’s space (asterisk). Red blood cells are absent. (C) Dehydrated Thiel embalmed renal cortex. Renal histology is similar to the fresh status. The glomeruli have a compact structure and cells have a dens appearance but their shape remains irregular (black arrows). There is no expansion of the interstitial space. (d) Reperfusion of Thiel embalmed dehydrated renal cortex with PP. Reperfusion causes dilation of the glomerular vessels (black arrow) and expansion of Bowman’s space (asterisk) and interstitial space (arrowhead). Tubular cells remain irregular and flat (white arrow) as in the dehydrated status suggesting that the perfusate does not interact with these cells. (e) Reperfusion of Thiel embalmed dehydrated renal cortex with diluted PEG. Glomerular vessels (arrow) and Bowman’s space (asterisk) are dilated. There is a fluid shift into the interstitial space (arrowhead). Widening of subepithelial space (white arrow) of enlarged tubular cells presumably due to uptake of the water component of diluted PEG. This causes narrowing of tubular lumina (star). F-J: Orcein staining (magnification: x 1000). (F) Fresh renal cortex. The wavy internal elastic lamina of arterioles is deep red brown (black arrow). The tunica adventitia is lightly stained (arrowhead). (G) Thiel embalmed renal cortex. More than half of the internal elastic lamina is flattened suggesting fluid accumulation in the vessel wall (black arrow). Partly detached endothelial cells (arrowhead). (H) Dehydrated Thiel embalmed renal cortex. Return of the wavy appearance of the internal (black arrow) and external (arrowhead) elastic membranes due to fluid loss. (I) Reperfusion of Thiel embalmed dehydrated renal cortex with PP. Partial flattening of the internal elastic lamina probably due to an increase of perfusate in the vessel wall (black arrow). (J) Reperfusion of Thiel embalmed dehydrated renal cortex with diluted PEG. The internal elastic lamina lost parts of its scalloped appearance which may be caused by a build-up of diluted PEG in the wall (black arrow).