Caecal Development in Kuttanad Duck (Anas Platyrhynchos Domesticus)

Abstract

Caecum, the largest part of duck's intestine has an important role in liquid absorption, cellulose digestion and defensive mechanism. Age related changes in the histomorphology of the caeca in Kuttanad ducks were studied in 72 birds from day-old to adult at fortnight intervals. After recording the biometry and gross features, the material was fixed in neutral buffered formalin and standard procedures were adopted for histological and histochemical studies. The paired caeca extended cranially from the ileo-colic junction. Each caecum showed three regions, viz., the base, middle part and an apex. The apical portion was caudally directed and free. In day-old birds, the caecum had a uniform diameter .The adult length was attained by eight weeks of age. Histologically, ileo-caecal-colic junction showed a papilla-like protrusion made up of circular smooth muscle layer. Large nerve bundles were found in the inner circular layer of tunica muscularis in this region. Mucosa of the caecum carried tooth shaped villi, which were more prominent and longer in the basal part. Their height reduced towards the middle portion and again increased in the apex in the non-distended caecum. In day- old birds, histological picture was same as in the adult except in that there was no lymphatic tissue in the lamina propria. Lamina epithelialis was formed of simple columnar epithelium with goblet cells, the number of which decreased towards apex. Lymphatic tissue decreased towards the apex. Lamina propria was separated from the submucosa by a thin muscularis mucos. At the basal region, tunica muscularis was extremely thick forming the caecal sphincter.