Histological and histochemical characteristics of the developing chicken (Gallus gallus domesticus) cecum.

Avian ceca play an important role in liquid absorption, cellulose digestion, and defensive mechanism. This study aims to demonstrate histological and histochemical characteristics of developing chicken cecum. For this purpose, 10 embryos on the 18th day of incubation, 10 chicks on hatching day and 10 chicks on the seventh day post-hatching were used. The histological sections prepared from proximal, middle, and distal parts of cecum were stained with Crossmon's triple stain, periodic-acid Schiff, Alcian blue (pH 2.5), Masson-Fontana's argentaffin silver stain and Gordon and Sweets's silver stain. Alpha-naphthyl acetate esterase (ANAE) and acid phosphatase (ACP-ase) were also demonstrated in the sections. In the proximal part, although the villi were rudimentary on the 18th day of incubation, well-developed villi were seen at seventh day post-hatching. In middle and distal parts, while it was seen that rudimentary folds appeared on the 18th day of incubation, mucosal folds were prominent and short villi were formed on the hatching day and seventh day post-hatching. Goblet cells and enteroendocrine cells were detected from the 18th day of incubation. The lymphoid follicles supported with reticular fibres were seen on the seventh day post-hatching in proximal cecum wall. While ACP-ase (+) lymphocytes were rarely observed, more ANAE (+) lymphocytes were in lymphoid follicles. As a result, development of cecum in chickens has been demonstrated by histological techniques in this study.