Development of Fungiform Papillae of the Mouse Tongue

A Scanning Electron Microscopic Study

Abstract

Development of the fungiform papillae of mice was studied with a scanning electron microscope. Mouse fetuses of gestational ages from 11.5 through 18.5 days and neonates aged one to 21 days were used. Three adult mice weighing about 30gm were used as controls.
1) On the 11.5th gestational day, the dorsum of the tongue was covered with polygonal cells with short microvilli. The surface of these cells was slightly elevated.
2) On the 12.5th day, hemispheroid cells were observed. Small eminences, which consisted of a number of hemispheroid cells, were formed on the dorsum after the 13.5th gestational day. It was observed that these small eminences gradually increased in size and developed to fungiform papillae.
3) On the 16.5th day, mesh-like microridges were found on the free surface of the cells which coverd the fungiform papillae. Desquamation or disappearance of the periderm was noted on the 17.5th day of gestation.
4) In one-day old neonates, outer taste pores were not yet present on the fungiform papillae. A little later outer taste pores appeared and gradually increased in number. In 14-day old mice, an outer taste pore was present on each fungiform papilla.
5) In some cases, outer taste pores disappeared form the fungiform papillae of the tongues of 21-day old mice, presumably because of some mechanical damage to the fungiform papillae.
6) The maximum diameter of the outer taste pore of 21-day old mice was 2.5±0.06μm S. D. (N=20).
Epithelial desquamation on the surface of the fungiform papillae was found around the outer taste pore at this age. The degree of desquamation varied considerably among the fungiform papillae. Both extrinsic and intrinsic factors may influence the degree of epithelial desquamation.