Abstract:
This study was done to compare foliate papillae in animals with different feeding
behavior; Rabbit (Lagomorpha) a hind-gut small herbivore; Dog (Carnivora) a
hind-gut omnivore; Donkey (Perissodactyla) a hind-gut large herbivore; Goat
(Artiodactyla) a fore-gut herbivore. From gross anatomy, histological, immunohistochemical and
scanning electron microscopy studies, it could be concluded that the epithelium of the foliate
papillae was non-keratinized in rabbit and dog, para-keratinized in donkey, due to the dry hay diet,
ortho-keratinized in goat leaf-like papillae, due to the presence of papillae over the surface and
its exposure to high mechanical stresses. The taste buds were present in rabbit, dog and donkey
foliate papillae and absent in goat leaf-like papillae. The taste bud structure, shape and size were
nearly the same in rabbit, dog and donkey from a histological view, They differed in distribution.
The taste buds were positive to anti-cytokeratin 18 in rabbit and donkey and negative in dog. The
ridges as well as grooves of the foliate papillae were widest at the donkey then the dog then the
rabbit, due to the relative size difference in the three animals. The salivary glands associated with
foliate papillae were large in number in dog, due to panting then donkey to facilitate eating of dry
hay more than rabbit and goat. The blood capillaries were more in the dog, due to panting and
heat regulation then in donkey, due to the need to supply glands to facilitate eating of dry hay.
Inflammatory cells were most common in donkey than dog, due to the wide grooves with large
amount of food and antigens. The tongue papillae functionally adapt according to the type of food
consumed and the nutritional habits of the mammals.
