Age features of topography and number of intestinal endocrinocytes in domestic duck

Abstract

The aim of the study was to determine the features of the topography and the number of the total population of endocrinocytes and enterochromaffin cells in the intestines of ducks during the first year of the postnatal period of ontogenesis. The experiments were performed on domestic ducks (Anas platyrhynchos domesticus) of black white-breasted breed (n = 5) 9 groups: 1-, 3-, 7-, 14-, 21-days-old, 1-, 2-, 6-month-old and 1-year-old. Determination of the total population of endocrine cells (argyrophilic) and enterochromaffin (argentaffin) was performed on histological specimens made from cross-sections of the middle section of the duodenum, jejunum, ileum, cecum and rectum, stained by Masson and Grimelius. The endocrine cells of 1- and 3-days-old ducks had a «superficial» location due to insufficient formation of crypts and villi. In older birds, in the duodenum, jejunum, and ileum, both argyrophilic and argentaffin APUD cells were localized mainly in crypts, and in the cecum and rectum, they were also in the epithelial layer of the villi. During the entire observation period, the highest content of both argyrophilic and argentaffin endocrinocytes in all intestines were found in 21-days-old ducks. Already at 3-days-old age, the total number of endocrine cells in various intestines corresponded to those of an adult bird. The highest number of argyrophilic and argentaffin endocrinocytes was found in the ileum and cecum, less in the rectum and jejunum, and the smallest number was in the duodenum. Enterochromaffin cells are the most common type of endocrinocytes in the ducks’ intestines, their relative content ranged from 40.1 to 97.5%. The highest relative content of argentaffin cells at 1-, 3- and 7-day-old was observed in the duodenum, at 14-day-old – in the duodenum and colon, at 21-day-old – in the rectum, at 1- and 2-month-old in jejunum, at the age of 6 month – in the duodenum, jejunum and caecum, and at the age of 1-year-old – in the ileum and cecum. In addition to argyrophilic endocrinocytes, which were located in the epithelium, other cells were found in the loose connective tissue of the villi base, the cytoplasm of which was also intensively impregnated with silver nitrate. Such cells were smaller and mostly oval in shape. Their cytoplasm was impregnated almost evenly around the nucleus and had no polarity in the location of the granules. Probably those were mast cells, which also contain bioamines, and, as well as enteroendocrinocytes, are found in the argyrophilic reaction.