ABSTRACT
A study of the differentiation in vitro of the mouse embryonic oesophageal epithelium. The effects of vitamin A and of hydrocortisone
Fragments of embryonic (18 days) oesophagus cultured in standard medium for 8 days achieved a minimum degree of keratinization.
Appropriate doses of absolute alcohol administered over the same period enhanced normal keratinization.
Vitamin A inhibited keratinization, and differentiation into multistratified epithelium or into a minimally keratinized epithelium took place.
The effect of vitamin A depends upon the duration of its administration.
Hydrocortisone in concentrations of between 1·1 μg/ml and 10 μg/cc inhibits keratinization in a similar way but with the difference that vacuolated and degenerating cells are found in some of the epithelial cultures.
Low concentrations of hydrocortisone (0·5 μg/ml) stimulate keratinization after 9 days of culture.
Vitamin A and hydrocortisone in combination appear to be toxic in some cases though they usually together inhibit keratinization in a manner similar to their separate effects. However, there is some evidence of synergistic activity.
When explants are treated first with hydrocortisone (0·5 μ g/ml) and later with vitamin A (6·6 i.u./ml) they show predominantly the influence of the vitamin, i.e. inhibition of keratinization. When the reverse treatment occurs, i.e. vitamin A followed by hydrocortisone, most explants show full keratinization.
These results show that it is the last-acting of two opposing influences that is effective in controlling the differentiation of cultured mouse oesophageal epithelium.
