Domestic pig head and neck arteries from the viewpoint of imaging methods and experimental surgery

The aim of this paper is to summarize the current knowledge of the anatomy of domestic pig head and neck arteries for the needs of experimental surgery and imaging methods in biomedical research and translational medicine. The potential of this large animal model seems to be valuable also for the xenotransplantation of certain organs. Demands for the knowledge of morphological differences between analogous human structures and particular breeds are growing also in connection with the need for more precise planning of experiments or interpretation of the results. Deepening anatomical knowledge is allowed also by the development of imaging methods. The search was performed using the keywords "domestic pig" and "arteries of the head and neck" in the MEDLINE database, PubMed interface.

Bony canal and grooves of the middle meningeal artery: mythic structures in anatomy and neurosurgery?

BACKGROUND: It has been previously published that the frontal branch of the middle meningeal artery (MMA) is usually embedded in a bony canal (BC). Although the incidence of the BC was over 70%, this structure is currently omitted both in anatomical nomenclature and in most of the literature. We found the same gap pertaining to the grooves for the MMA on the skull base. The aims of our study were to assess the incidence and morphometry of the MMA BC and grooves on the skull base. MATERIALS AND METHODS: Computed tomography (CT) scans of 378 patients, 172 skull bases as well as 120 sphenoidal bones and 168 temporal bones, and 12 histological specimens from 3 men and 3 women and 3 different regions of the MMA course were assessed. RESULTS: Based on CT scans, the incidence of the BC was 85.44% and was significantly higher in females than in males. Most of the canals and grooves were bilateral. The mean canal length was 17.67 mm, the mean transverse diameter 1.33 mm, and the mean distance from the superior orbital fissure (dFOS) was 26.7 mm. In the skull bases, the BC incidence was 70.07%, the mean canal length 10.74 mm, and the mean dFOS was 19.16 mm. The groove for the MMA on the temporal and sphenoidal bones was present in 99.42% and 95.35%, respectively. Histological specimens confirmed the presence of the MMA and accompanying vein/s. CONCLUSIONS: Based on our results, we suggest the addition of the BC and grooves for the middle meningeal vessels to the upcoming version of the Terminologia Anatomica.

Distribution of Connective Tissue in the Male and Female Porcine Liver: Histological Mapping and Recommendations for Sampling.

The pig is a large animal model that is often used in experimental medicine. The aim of this study was to assess, in normal pig livers, sexual dimorphism in the normal fraction of hepatic interlobular and intralobular connective tissue (CT) in six hepatic lobes and in three macroscopical regions of interest (ROIs) with different positions relative to the liver vasculature. Using stereological point grids, the fractions of CT were quantified in histological sections stained with aniline blue and nuclear fast red. Samples (415 tissue blocks) were collected from healthy piglets, representing paracaval, paraportal and peripheral ROIs. There was considerable variability in the CT fraction at all sampling levels. In males the mean fraction of interlobular CT was 4.7 ± 2.4% (mean ± SD) and ranged from 0% to 11.4%. In females the mean fraction of the interlobular CT was 3.6 ± 2.2% and ranged from 0% to 12.3%. The mean fraction of intralobular (perisinusoidal summed with pericentral) CT was <0.2% in both sexes. The interlobular CT represented >99.8% of the total hepatic CT and the fractions were highly correlated (Spearman r = 0.998, P <0.05). The smallest CT fraction was observed in the left medial lobe and in the paracaval ROI and the largest CT fraction was detected in the quadrate lobe and in the peripheral ROI. For planning experiments involving the histological quantification of liver fibrosis and requiring comparison between the liver lobes, these data facilitate the power analysis for sample size needed to detect the expected relative increase or decrease in the fraction of CT.

[Experimental processing of corrosion casts of large animal organs]. / Experimentální príprava korozivních preparátu orgánu velkého zvírete.

INTRODUCTION: Corrosion casts (CCs) are used for the visualization and assessment of hollow structures. CCs with filled capillaries enable (with the help of imaging methods) to obtain data for mathematical organ perfusion modelling. As the processing is more difficult in case of organs with greater volume of the vasculature, mainly organs from small animals have been cast up to now. The aim of this study was to optimize the protocol of corrosion casting of different organs of pig. Porcine organs are relatively easily accessible and frequently used in experimental medicine. METHOD: Organs from 10 healthy Prestice Black-Pied pigs (6 females, body weight 35-45 kg), were used in this study (liver, spleen, kidneys and small intestine). The organs were dissected, heparin was administered into the systemic circulation and then the vascular bed of the organs was flushed with heparinized saline either in situ (liver) or after their removal (spleen, kidney, small intestine). All handling was done under the water surface to prevent air embolization. The next step was an intraarterial (in case of the liver also intraportal) administration of Biodur E20® (Heidelberg, Germany) resin. After hardening of the resin the organ tissue was dissolved by 15% KOH and the specimen was rinsed with tap water. Voluminous casts were stored in 70% denatured alcohol, the smaller ones were lyophilized. The casts were assessed with a stereomicroscope, computed and microcomputed tomography (CT and microCT), a scanning electron microscope (SEM) and high-resolution digital microscope (HRDM). RESULTS: High-quality CCs of the porcine liver, kidneys, spleen and small intestine were created owing to the sophisticated organ harvesting, the suitable resin and casting procedure. Macroscopic clarity was improved thanks to the possibility of resin dying. Scanning by CT was performed and showed to be a suitable method for the liver cast examination. MicroCT, SEM and HRDM produced images of the most detailed structures of vascular bed. Despite the fact that SEM seems to be an irreplaceable method for CCs quality control, it seems that this modality could be partly replaced by HRDM. MicroCT enabled to obtain data about three-dimensional layout of the vascular bed and data for mathematical modelling of organ perfusion. With regard to the quality of the CCs, they could also be used to teach human anatomy. CONCLUSIONS: The protocol of the corrosion casting of the porcine liver, kidneys, spleen and small intestine CCs was optimized. Thanks to different imaging methods, the CCs can be used as a source of data on three-dimensional architecture of the vascular bed. These data can be used for mathematical modeling of organ perfusion which can be helpful for example for optimization of organ resections.Key words: corrosion casts microvasculature Biodur E20® domestic pig animal model.

Porcine liver vascular bed in Biodur E20 corrosion casts.

BACKGROUND: Pigs are frequently used as animal models in experimental medicine. To identify processes of vascular development or regression, vascular elements must be recognised and quantified in a three-dimensional (3D) arrangement. Vascular corrosion casts enable the creation of 3D replicas of vascular trees. The aim of our study was to identify suitable casting media and optimise the protocol for porcine liver vascular corrosion casting. MATERIALS AND METHODS: Mercox II® (Ladd Research, Williston, Vermont, USA) and Biodur E20® Plus (Biodur Products, Heidelberg, Germany) were tested in 4 porcine livers. The resins (volume approximately 700 mL) were injected via the portal vein. Corrosion casts were examined by macro-computed tomography, micro-computed tomography and scanning electron microscopy. RESULTS: For hepatectomies, the operating protocol was optimised to avoid gas or blood clot embolisation. We present a protocol for porcine liver vascular bed casting based on corrosion specimens prepared using Biodur E20® epoxy resin. CONCLUSIONS: Only Biodur E20®Plus appeared to be suitable for high-volume vascular corrosion casting due to its optimal permeability, sufficient processing time and minimum fragility. Biodur E20® Plus is slightly elastic, radio-opaque and alcohol-resistant. These properties make this acrylic resin suitable for not only vascular research but also teaching purposes.

Focal histopathological progression of porcine experimental abdominal aortic aneurysm is mitigated by atorvastatin.

AIM: Observational studies in human patients and animal experiments suggested that statins have a potential in slowing the growth of small abdominal aortic aneurysms (AAA). Our aim was to quantify histological postoperative changes of AAA in porcine experimental model of AAA with and without administration of atorvastatin. METHODS: The AAA was induced by intraaortic infusion of porcine pancreatic elastase and subrenal application of plastic cuff. The AAA statin group (N.=14) received atorvastatin 1 mg/kg daily for 28 days, the other AAA group (N.=13) did not. The aortic diameter was measured by ultrasonography. Aortic samples were described using eleven quantitative histological parameters and compared with healthy aortae. RESULTS: There was no difference in aortic diameter between the AAA with statin when compared to AAA without statin. Administration of atorvastatin led to a better postoperative histological condition of the aortic elastin network, preservation of contractile phenotype of vascular smooth muscle, a higher density of vasa vasorum, it prevented thickening of intima and media. The increase in wall thickness in AAA without atorvastatin has not been accompanied by a proportional increase in number of vasa vasorum. CONCLUSION: The effects of atorvastatin seem to prevent the histopathological progression of AAA.

[Pharmacological influencing of abdominal aortic aneurysm model - animal experimental study, primary results]. / Farmakologické ovlivnení modelového aneuryzmatu brisní aorty - experiment na zvíreti, prvotní výsledky.

INTRODUCTION: The aim of our work was to influence growth and histological changes in the wall of an experimentally induced aneurysm of the abdominal aorta in a large laboratory animal (domestic pig) by administering atorvastatin (3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor). MATERIAL AND METHODS: Within the scope of the above mentioned experimental work, we compared the growth rate of the aneurysm between the group influenced by statin administration (n=14) and the group without any pharmacological treatment (n=13). We also compared histological changes in the structure of the aortic wall in both groups with aneurysm and the wall of the aorta without aneurysm (n=6). RESULTS: During the 4-week follow-up, we did not prove a statistically significant difference in the growth rate of aneurysms between the above mentioned groups. The histological structure of the aneurysm walls, however, differed between the two groups. The structure of the wall in the group of animals influenced by statin administration resembled the structure of the aortic wall without aneurysm. CONCLUSION: The results presented demonstrate that statins do influence the composition of the aortic wall. In our opinion, the administration of statins could lead to changes resulting in a more stable aneurysmatic wall. We believe that patients with smaller aneurysms who are not indicated for surgery or endovascular treatment could be treated with statins. Stabilization of the aneurysmal wall could slow down the growth of the aneurysm and prevent its rupture.