Functional and morphological observations on the microvascular structure of the filiform and fungiform papillae in the cat tongue.

The purpose of this study was to undertake a three-dimensional comparative observation of the microvascular cast specimen (MVCS) of the filiform papillae (FiP) and fungiform papillae (FuP) on the dorsal surface of the cat tongue. By means of the corrosive resin casting technique, the MVCS of the FiP and FuP of the cat tongue were prepared and examined in detail under the scanning electron microscope (SEM). The numerous FiP and FuP distributed sporadically among the different types of the FiP were found on the entire dorsal surface of each cat tongue. A single FiP consisted of a main process (MP) which contained a large spoon-shaped concave network process and the accessory process (AP) contained a bundle of spine-like processes, arranged in a circle at the basal margin of the MP. The FiP can be classified into five types (Type I-V) according to the shape and size of the MP and numbers of the AP. Each FuP consisted of a single MP which contained an ovoid head and many AP surrounding the basal margin of the MP. The FuP can be classified into four types (FuP I-IV) according to the shape and size of the MP and numbers of the AP. The MP of the FuP, a sense organ for taste, of the cat tongue was considered to be a transformed type from the MP of the FiP, which acquires the ability to masticate and swallow functionally.