Adaptation of colon microvascularization to different degrees of ischaemia –an anatomo surgical study.

The aim of this work was to study the capacity of the arterialplexuses of the colonic wall to tolerate different degrees ofischaemia and to study the histological mucin secretion and cellularproliferation changes induced by different degrees of ischaemia.Ninety human colons and 95 dogs were used for this work. Thehuman colons were injected through inferior mesenteric artery.Before perfusion, in 34 cases, marginal artery was excised for 5cmand 8cm in length. Dog’s colons were injected through caudalmesenteric artery (c.m.a.). 53 dogs were submitted to fourischaemic degrees: ischaemia 1- c.m.a. ligation; ischaemia 2- c.m.a.and cranial rect al artery ligation; ischaemia 3- c.m.a. ligation andmarginal artery excision for 5cm length; ischaemia 4- c.m.a.ligation and marginal artery excision for 8cm length. The organswere studied by clearing method, microangiography, scanningelectronic microscopy in corrosion casts and histology. The rich andhomogeneous arterial plexuses of dog’s and man’s colonic wallhave a limited functional value because they are not good ways ofcollateral circulation when marginal artery is excised. In dogs,complications were only observed in those submitted to the mostsevere degree of ischaemia. Normal epithelium segregatessulphomucins but colonic ischaemia induces the production ofsialomucins in an amount directly proportional to lesion severity.Moderate and severe ischaemia determine an increase of themucosal proliferating cells fraction producing DNA. In patientswith suspicious colonic chronical ischaemia the study of mucinsand cells proliferation in fragments of mucosal biopsies obtained bycolonoscopy may offer one more contribution to diagnosis andevaluation of lesions severity, mainly when a normal arteriogramwas obtained.