THE INTEGRATIVE SEGMENT OF THE QUAIL COTURNIX-COTURNIX-JAPONICA - OCCURRENCE AND DISTRIBUTION OF CARBONIC-ANHYDRASE AND COMPLEX CARBOHYDRATES

As part of a more extensive study into the involvement of carbonic anh ydrase in avian excretory function, the occurrence and distribution of this enzyme was investigated in the quail integrative segment. The in tegrative segment represents, in birds, that part of the intestinal tr act where ureteral urine undergoes postrenal modification to form defi nitive urine. To define the structural peculiarities within the intest inal epithelium, the constituent parts, namely cloaca, rectum and caec um, as well as the posterior ileum, were examined histochemically to v isualise complex carbohydrates. The histochemical findings for carboni c anhydrase activity were compared with the results from a correlative immunohistochemical approach performed with a specific antiserum to a vian CA II. Most of the enzyme activity unhomogeneously distributed in the intestinal enterocytes within the mucosal epithelium, was shown t o be due to the cytosolic isoenzyme CA II. Additional carbonic anhydra se isoenzymes, distinct from CA II, seem to occur both at the enterocy te brush border and at the smooth muscle layer of the muscularis exter na.