THE INFLUENCE OF HYDROCORTISONE ON THE ACTION OF EXCESS VITAMIN A ON LIMB BONE RUDIMENTS IN CULTURE

Abstract

The effect of hydro-cortisone has been studied in organ cultures of the cartilaginous long-bone rudiments from 7-day chick embryos and of the well ossified limb-bones from late foetal mice. In the chick rudiments, which grow rapidly in culture, the growth-rate was much reduced by hydrocortisone; in the late foetal mouse bones, which grow very little in culture, hydrocortisone had no obvious effect on growth but arrested resorption of the cartilage. These effects resemble those described by others in the skeleton of animals treated with cortisone or hydrocortisone. The influence of hydrocortisone on the response of the chick and mouse explants to excess vitamin A was investigated. In the presence of excess vitamin A alone, cartilage (chick, mouse) and bone (mouse) disintegrated, but when hydrocortisone also was added to the medium, this dissolution of the intercellular material was much retarded, though not suppressed. The retardative action of hydrocortisone on the changes produced by excess vitamin A in skeletal tissue in culture, contrasts sharply with the strongly additive effect of the 2 agents on the skeleton in the intact animal. It is suggested that this discrepancy between the results obtained in vitro and in vivo is probably due to systemic factors that operate in the body but are eliminated in organ cultures.