Structure of the myenteric plexus in normal and diseased human ileum analyzed by X-ray virtual histology slices

BACKGROUND The enteric nervous system(ENS)is situated along the entire gastrointestinal tract and is divided into myenteric and submucosal plexuses in the small and large intestines.The ENS consists of neurons,glial cells,and nerves assembled into ganglia,surrounded by telocytes,interstitial cells of Cajal,and connective tissue.Owing to the complex spatial organization of several interconnections with nerve fascicles,the ENS is difficult to examine in conventional histological sections of 3-5μm.AIM To examine human ileum full-thickness biopsies using X-ray phase-contrast nanotomography without prior staining to visualize the ENS.METHODS Six patients were diagnosed with gastrointestinal dysmotility and neuropathy based on routine clinical and histopathological examinations.As controls,fullthickness biopsies were collected from healthy resection ileal regions after hemicolectomy for right colon malignancy.From the paraffin blocks,4-μm thick sections were prepared and stained with hematoxylin and eosin for localization of the myenteric ganglia under a light microscope.A 1-mm punch biopsy(up to 1 cm in length)centered on the myenteric plexus was taken and placed into a Kapton®tube for mounting in the subsequent investigation.X-ray phase-contrast tomography was performed using two custom-designed laboratory setups with micrometer resolution for overview scanning.Subsequently,selected regions of interest were scanned at a synchrotron-based end-station,and high-resolution slices were reported.In total,more than 6000 virtual slices were analyzed from nine samples.RESULTS In the overview scans,the general architecture and quality of the samples were studied,and the myenteric plexus was localized.High-resolution scans revealed details,including the ganglia,interganglional nerve fascicles,and surrounding tissue.The ganglia were irregular in shape and contained neurons and glial cells.Spindle-shaped cells with very thin cellular projections could be observed on the surface of the ganglia,which appeared to build a network.In the patients,there were no alterations in the general architecture of the myenteric ganglia.Nevertheless,several pathological changes were observed,including vacuolar degeneration,autophagic activity,the appearance of sequestosomes,chromatolysis,and apoptosis.Furthermore,possible expulsion of pyknotic neurons and defects in the covering cellular network could be observed in serial slices.These changes partly corresponded to previous light microscopy findings.CONCLUSION The analysis of serial virtual slices could provide new information that cannot be obtained by classical light microscopy.The advantages,disadvantages,and future possibilities of this method are also discussed.

Ex vivo evaluation of IVUS-VH imaging and the role of plaque structure on peripheral artery disease

Peripheral artery disease(PAD)results from the buildup of atherosclerotic plaque in the arterial wall,can progress to severe ischemia and lead to tissue necrosis and limb amputation.We evaluated a means of assessing PAD mechanics ex vivo using ten human peripheral arteries with PAD.Pressure-inflation testing was performed at six physiological pressure intervals ranging from 10 to 200 mmHg.These vessels were imaged with IVUS-VH to determine plaque composition and change in vessel structure with pressure.Statistical analysis was performed to determine which plaque structures and distributions of these structures had the greatest influence on wall deformation.We found that fibrous plaque,necrotic core,and calcification had a statistically significant effect on all variables(p<0.05).The presence of large concentrations of fibrous plaque was linked to reduced vessel compliance and ellipticity,which could lead to stent fractures and restenosis.For the plaque distribution we found that clustered necrotic core increased overall compliance while clustered calcification decreased overall compliance.The effect of plaque distribution on vessel wall deformation must be considered equally important to plaque concentration.