Functional and angioarchitectural structure and classification of lingual papillae on the postero-dorsal surface of the beagle dog tongue.

A scanning electron microscopic study was done of the three-dimensional, morphological structure and classification by means of microvascular cast specimens (MVCS) of the filiform (FiP), fungiform (FuP) and circumvallate papillae (CvP) on the postero-centro-peripheral, and conical papillae (CoP) on the posteroperipheral-dorsal surface of the caudal portion of the beagle dog tongue. The characteristics and functional arrangement of each lingual papilla were as follows: the FiP densely and geometrically covered the entire postero-centro-peripheral dorsal surface. The outer structure of the FiP, consisting of both the ascending and descending branches from their tributaries, was a spoon-like capillary micro-network structure with a sharp arrowhead-like top inclined posteriorly. On the other hand, the outer structure of the FuP, appearing sporadically on the oblique lines of the FiP, was of round form consisting of a capillary microvascular network structure. The FuP, consisting of ascending and descending branches similar to the FiP, were distributed sporadically and geometrically on oblique lines in a V-form running from both peripheral sides to postero-central direction on the FiP A group of three CvPs were arranged on oblique lines in a V form from the peripheral to the postero-central region on the postero-dorsal surface. The outer shape of the microvascular network structure of the CvP was a round fence-like structure surrounding the papillary body and the papillary body consisted of an inner semi-spherical microvascular network structure. The CoP densely covered the entire postero-peripheral-dorsal surface. The exterior figure of the conical micro-network structure, consisting of both the ascending and descending branches of the CoP, was a cone-like capillary network structure, and the sharp tops were inclined posteriorly. They were classified into three types: large (L-CoP), medium (M-CoP) and small (S-CoP) according to the morphological characteristics in shape, size and the distributive position. It was conjectured that the FiP play a concentric functionally important role in transporting food and liquid from both sides in a postero-central direction towards the pharynx. And, on the other hand, the FuPs play an assistant role in receiving gustatory sensations from the masticated food and liquid on the central dorsal surface. The CoP play a functionally important role on the postero-peripheral-dorsal surface, in transporting food and liquid towards the pharynx and a complementary role of the CvP is to receive gustatory sensations from masticated food and liquid on the postero-peripheral-dorsal surface of the caudal portion of the beagle dog tongue.