The mechanical features of the colonic wall change with increasing age.12,13 Combined barostat-manometry studies of the entire colon have demonstrated that compliance is lowest in the sigmoid and descending colon and greatest in the transverse and ascending colon.13 This difference in mechanical properties between the right and left sides might partly account for the left-sided predominance of diverticulosis.14
Structural components of the extracellular matrix of the colonic wall, including collagen, elastin, and proteoglycans, are likely to be important in maintaining the strength and integrity of the colonic wall.15,16 Changes in these components of the bowel wall, such as damage and breakdown of mature collagen, and consequently its immature synthesis can lead to a change in bowel consistency.17 These changes may be related to a genetic predisposition such as that seen in Ehlers-Danlos and Marfan's syndromes, which may be responsible for the occurrence of diverticula at an early age, or to the natural course of the aging process itself. In one study, it has been reported that collagen fibrils in the left colon are smaller and more tightly packed than those in the right colon with increasing age, and that this difference is accentuated in diverticular disease.16
The thickening of longitudinal and circular muscles in diverticular disease is neither hyperplastic nor hypertropic, but appears to be related to a contractile state. An increase in the number of elastic fibers has been observed only in the longitudinal muscle.18 It has been suggested that this process is responsible for longitudinal contraction, with subsequent thickening of both muscle layers.18 All these changes, along with elastin deposition in the teniae coli, lead to an irreversible state of contracture, with substantial bowel shortening, which may result in decreased resistance of the colon wall to persistent intraluminal pressure.19
The mechanical features of the colonic wall change with increasing age.12,13 Combined barostat-manometry studies of the entire colon have demonstrated that compliance is lowest in the sigmoid and descending colon and greatest in the transverse and ascending colon.13 This difference in mechanical properties between the right and left sides might partly account for the left-sided predominance of diverticulosis.14Structural components of the extracellular matrix of the colonic wall, including collagen, elastin, and proteoglycans, are likely to be important in maintaining the strength and integrity of the colonic wall.15,16 Changes in these components of the bowel wall, such as damage and breakdown of mature collagen, and consequently its immature synthesis can lead to a change in bowel consistency.17 These changes may be related to a genetic predisposition such as that seen in Ehlers-Danlos and Marfan's syndromes, which may be responsible for the occurrence of diverticula at an early age, or to the natural course of the aging process itself. In one study, it has been reported that collagen fibrils in the left colon are smaller and more tightly packed than those in the right colon with increasing age, and that this difference is accentuated in diverticular disease.16The thickening of longitudinal and circular muscles in diverticular disease is neither hyperplastic nor hypertropic, but appears to be related to a contractile state. An increase in the number of elastic fibers has been observed only in the longitudinal muscle.18 It has been suggested that this process is responsible for longitudinal contraction, with subsequent thickening of both muscle layers.18 All these changes, along with elastin deposition in the teniae coli, lead to an irreversible state of contracture, with substantial bowel shortening, which may result in decreased resistance of the colon wall to persistent intraluminal pressure.19
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