Anatomical and neurohistological observations on the tongue of 60 mm embryo of opossum, Didetphis marsupialis.

The anatomy, histology and innervation of the tongue of 60 mm embryo of opossum, Didelphis marsupialis have been described. The tongue measures 13 mm in length and 4.5 mm in breadth. The tip of the tongue is somewhat pointed and bordered by soft fringe of simple filiform papillae which are probably tactile in function. The fungiform papillae are small rounded bead-like structures scattered over the dorsum. The circumvallate papillae are three in number and arranged in an inverted V-shape. Taste buds are developed over the dorsum of fungiform papillae. The foliate papillae are concealed. The filiform papillae in various stages of development are seen over the entire dorsum. The circumvallate papillae are not fully developed. Mucous glands and their ducts are well-developed. The innervation of the tongue of 60 mm embryo of opossum is almost similar to that of other mammals. The dorsal side of the tongue is covered with thick squamous epithelium and is innervated by thick nerve fibres. The ventral surface is thin and comparatively poor in nerve supply. The skeletal muscles and connective tissue are richly innervated by thick and thin nerve fibres. A large number of ganglion cells lie singly or in irregular groups in the plexuses of the intermingling nerve fibres. The filiform papillae are heavily innervated by thick nerve fibres. Nerve elements could not be observed in the circumvallate papillae. Fungiform papillae are also provided with fine nerve fibres. A few nerve fibres and nerve bundles are seen in the gullet region.