Innominate grooves of the colon: Histological reappraisal

Abstract

Background: Innominate grooves (IGs) in the colon are ubiquitous structures limiting anthemic folds. The histology of the crypts in anthemic folds is well known but the histology of IGs has remained unattended. In this study, IG crypts in the normal mucosa and in ulcerative colitis (UC) were analyzed. Patients and Methods: IGs displayed a single central-lumen with merging tributary crypts. The number of merging tributary crypts, at both sides and at the bottom of the central lumen, were quantified in 60 IGs: 30 in normal colons and 30 in UC. Results: A total of 152 (median=5) tributary crypts were found merging in the 30 IGs in the normal colon, and 170 (median=5) in the 30 IGs in UC. The difference was non-significant (p=0.08012). Conclusion: Chronic inflammation did not influence the frequency of tributary crypts in IGs. The shape and the length varied considerably in the 60 IGs. Given that the chief putative physiological function of IGs is the expansion of the colon when submitted to increased intraluminal pressure, it is not inconceivable that following that demand, IGs act as hinges that permit grooves to level with the rest of the surrounding mucosa.