THE COLONIC GROOVE IN THE PLAINS VISCACHA (LAGOSTOMUS MAXIMUS): A MORPHOLOGICAL AND HISTOCHEMICAL STUDY

TANO DE LA HOZ M.F.; FLAMINI, M. A.; DÍAZ A.O.

Encuentro; X Encuentro Anual de Biólogos en Red; 2015

The ascending colon of several herbivorous mammals has a longitudinal colonic groove, which is used as a route of retrograde transport of a mixture of bacteria and mucus. The objective of this work was to perform a morphological and histochemical study of the colonic groove of L. maximus. Sections of ascending colon were subjected to histological techniques and histochemical procedures for glycoconjugates (GCs) identification (PAS; KOH/PA*S, PA/Bh/KOH/PAS; KOH/PA*/Bh/PAS; AB pH 2.5, 1.0 and 0.5; AT pH 5.6 and 4.2). The groove originated close to the ileocecal junction and was extended along the mesenteric side of the ascending colon. The groove walls were formed by ridges and contained arteries and prominent sinusoid-like veins. The tunica muscularis showed an increase in width and separation into individual bundles beneath the groove. The histochemical analysis revealed significant differences between the glycosylation pattern of goblet cells present on the groove and those of the outside of the groove. Unlike the colonic mucosa, the groove was rich in goblet cells containing a high proportion of sulfated GCs. The PA/Bh/KOH/PAS technique showed an abrupt change in the histochemical profile of the goblets cells, which presented a negative reaction in the groove and a strong positive reaction in the rest of the colonic mucosa. The specific goblet cells glycosylation in the area of the colon possessing the ridges suggest that the mucus has a role in the functioning of the groove probably related to the high density of bacteria present in this region.