カヤネズミ Micromys minutus の舌乳頭の走査電顎的研究

Abstract

The tongue and lingual papillae of the twelve old world harvest mice are observed by light and scanning electron microscope. The tongue is long, narrow, and thick, and tapered in shape. The oral part of the tongue is long, the pharyngeal part short. Sulcus medianus lingua is present anteriorly. In the central portion of the tongue, there is a lingual prominence which is covered with large filiform papillae arranged in rosette-shape. There is a sulcus medianus lingua, but no traces of the foramen caecum linguae and sulcus terminals. Four types of papillae are present on the dorsal surface of the old world harvest mouse tongue ; the filiform, fungiform, foliate and vallate papillae. The filiform papillae on the old world harvest mouse tongue are classified into three types : small, large filiform and conical papilla. The anterior half of the tongue is covered with a number of small filiform papillae. Only frontal side of those basal part is covered by the sheath which is keratinized in scale shape. The large filiform papillae on the anterior region of the lingual prominence are larger than those on the other parts, and arranged in rosette-shape. The posterior dorsal surface of the tongue is covered with the conical papillae. The fungiform papillae are scattered among filiform papillae on the dorsal surface, except lingual margin and lingual prominence. The foliate papillae of "acinar type", which have three grooves, are located on the anterior of the base of the glossopalatine fold. The only one vallate papilla is located in the posterior midline of the tongue. The papilla shows an appearance of the sunken type as seen in those of lower mammalian, as such kangaroo and duckbill. The papilla, which is cone-like in shape, is not recognizable on the dorsal surface since that is covered by an overlying epithelial fold. The trench communicates with the oral cavity through a small orifice, which is located in the central portion of the papilla region. The mucous glands open into the pharyngeal part without lingual papillae.