The purpose of this study was to investigate the most effective culturing conditions to study the process of differentiation of the taste buds (TB) and the contribution of the ganglia to it.
Small pieces of the tongue of the Wistar strain rats including the circumvallate papilla (CP) were cultured with or without the IX and X cranial ganglia. They were cultured being rocked in the humidified atmosphere of 50% O2-45% N2-5% CO2 at 37.. and observed with light and electron microscope.
The CP of the 17-day-old rat fetuses were cultured with or without the ganglia, using the BM-3 medium, consisting of 50% of HamF 12+DMEM (1: 1) and 50 of fetal bovine serum, supplemented with 7, 500. μg/ml of dextrose, 50IU/ml of penicillinG, 50. μg/ml of streptomycin, 150 μg/ml of ascorbate, 5. μg/ml of insulin and 200ng/ml of NGF. At this stage the fetuses showed. E neither TB nor innervation of the epithelium of the CP. The form of the CP with an epithelial structure was maintained well with the ganglia and not well without the ganglia. A bundle of nerve fibers ran along the epithelium and innervated it. The innervated epithelial cells were discriminated from the surrounding cells. In the hydrocortisone-added (1. μg/ml) BM-3 medium, the growth of the CP was inhibited and the epithelium was highly keratinized. But in the unkeratinized part of the side of the CP, large light cells with microvilli were observed, being discriminated from the surrounding epithelial cells. These cells had some characteristics common to the type 3 TB cell. It was concluded that the culture of the 17-day-old rat fetuses using the hydrocortisoneadded (1. μg/ml) BM-3 medium was the most appropriate condition for clarifying the interaction between the epithelium and the nerves and for studying the differentiation of the TB.