Ultrastructural localisation and size distribution of collagen fibrils in Glisson's sheath of rat liver: implications for mechanical environment and possible producing cells

Abstract

The ultrastructure and size distributions of collagen fibrils in Glisson's sheath were investigated in the rat liver to analyse the mechanical environment around the fibrils and their possible cells of origin. Glisson's sheath was found to contain 2 populations of collagen fibrils with different diameters and distinct localisations, namely fibroblast-associated and bile epithelium-associated. Fibroblast-associated collagen was composed of fibrils arranged in bundles and constituted the majority of the collagen in Glisson's sheath. Bile epithelium-associated collagen was represented by small dispersed groups of fibrils just beneath the basement membrane of the bile duct. The basement membrane of the bile duct was frequently reduplicated into a few or as many as 10 layers of laminae densae, with scattered collagen fibrils between these laminae. The diameters of the fibrils of both groups of collagen increased in relation to the calibre of the bile duct, whereas at any given place in Glisson's sheath bile epithelium-associated collagen fibrils had a smaller diameter compared with those of the fibroblast-associated fibrils. The increment in fibril diameter along the bile duct is considered to be correlated with the increase in mechanical stress acting on Glisson's sheath. The difference in diameter between the 2 populations as well as the incorporation of fibrils between the laminae densae of the basement membrane of the bile duct supports the view that the bile epithelium-associated collagen is produced by the epithelial cells of the bile duct, thus having a different origin from that of fibroblast-associated collagen. These findings provide the first evidence that the epithelial cells of the interlobular bile duct produce fibril-forming collagen. Furthermore, it is suggested that cholestasis stimulates the epithelial cells of interlobular bile duct to increased synthesis of fibril-forming collagen that is also produced by these cells under physiological conditions.

Structural and mechanical architecture of the intestinal villi and crypts in the rat intestine: integrative reevaluation from ultrastructural analysis

“…Considering the results in the Glisson's sheath by Hosoyamada et al (2000) the difference in diameter of collagen fibrils among the different parts of the intestinal wall probably reflect a high difference among the cells producing them. The fibroblasts in the lower LPM and TSM have distinctly different ultrastructures and different abilities to produce collagen fibrils as suggested by the different amounts of collagen fibrils.…”

“…Recently Hosoyamada et al (2000) studied the ultrastructure of connective tissue in Glisson's sheath of the rat liver, and reported that the variations in diameter of fibrils in Glisson's sheath is related to two different components. The first, the fibril diameter, is correlated with the caliber of the bile duct, most probably corresponding to the decrease in mechanical stress along the bile duct tree.…”

“…Especially in the arteries, perfusion pressure in the arterial lumina would expand the arterial wall to counterbalance the wall tension developed by the smooth muscle cells and extracellular matrices (Inokuchi et al 2001), resulting in smoothly expanded lamina elastica interna in contrast to artificially wrinkled elastic lamina usually found after immersion fixation without perfusion. Improved ultrastructural studies employing perfusion fixation have revealed new insights into the mechanical dynamics of visceral ultrastructure in the renal glomerular mesangium (Sakai and Kriz 1987), renal proximal tubule (Hijikata and Sakai 1991), renal glomerular podocytes , arterial endothelium (Sakai and Kobayashi 1992;Kobayashi and Sakai 1993), and hepatic interstitium (Hosoyamada et al 2000). , and TSM (c).…”

“…In the ileum, the bundles of collagen fibrils in the lower LPM and TSM (c) are less in amount than in the duodenum. CL central lymphatic, BC blood capillary, Evl villous epithelium, Ecr cryptal epithelium, SML smooth muscle layer, * smooth muscle cells of MM, ** superficial smooth muscle cells of SML, arrowhead perpendicular smooth muscle cells in LPM, 1800 times each Perfusion fixation has been recommended for ultrastructural research on various tissues including the spleen (Pictet et al 1969a(Pictet et al , 1969b, testis (Forssmann et al 1977), kidney (Kaissling and Kriz 1979;Sakai and Kriz 1987), elastic and muscular arteries (Kobayashi and Sakai 1994Sakai , 1997Sasaki et al 1995), placenta (Tanaka et al 1999), and liver (Hosoyamada et al 2000). Perfusion fixation preserves the ultrastructure of those tissues, which are mechanically affected by vascular and interstitial pressures.…”

Diffuse Reflectance Spectroscopy for Surface Measurement of Liver Pathology

“…In liver tissue, the absorption in the visible wavelength range is dominated by hemoglobin and bile, whereas water, lipid, and collagen are the main absorbers in the near-infrared wavelength range [14,16,19]. Blood-related absorption is represented by the effective absorption coefficient for a volume of tissue containing blood vessels as μ α Blood ( λ ) = C ( λ ) c HbT μ α HbT ( λ ), where c HbT is the total hemoglobin volume fraction, StO 2 is the level of hemoglobin oxygen saturation, and μ α HbT ( λ ) = StO 2 μ α HbO 2 ( λ ) + (1 - StO 2 ) μ α Hb ( λ ).…”