The present work aimed to gain more information about the ultrastructure of the rectal caeca of two avian species, the carnivorous common kestrel, Falco tinnunculus rupicolaeformis, and the omnivorous common moorhen, Gallinula chloropus. The mucosa of the rectal caeca of both studied species is divided into two layers; namely: the epithelial layer and the lamina propria. The epithelial layer is built up mainly of enterocytes. Besides that, such layer of F. t. rupicolaeformis is characterized by M-cells. Moreover, the lamina propria of F. t. rupicolaeformis is formed of connective tissue that is filled with numerous large and small lymphocytes and few crypts of Lieberkühn. In addition, the lamina propria of G. chloropus is formed of connective tissue, which has numerous crypts of Lieberkühn that are lined by enterocytes. The enterocytes of both studied species are columnar cells and are characterized by the presence of numerous microvilli on the luminal surface. The length of the microvilli of F. t. rupicolaeformis is of about 700 nm throughout the whole rectal length. However in G. chloropus, the microvilli of the proximal and middle parts of the rectal caeca have a uniform length of about 1 µm, while those of the distal part are shorter and their length is of about 600 nm.
Key words: avian rectal caeca, Falco tinnunculus rupicolaeformis, Gallinula chloropus, ultrastructure, M-cell, lymphocytes, enterocytes
|
