[Vitamin A, membranes and the differentiation of cells]

The paper deals with analysis of biochemical, morphological and physiological changes in vitamin A-deficiency. On the basis of this analysis a conclusion is drawn that vitamin A is first of all the factor of differentiation. The intercellular zone is considered to be the most probable sphere of its primary effect. Deficiency in vitamin A causes a change in a concentration and ratio of cations and glycosaminglycans in this zone, that results in disturbance of the intercellular interactions. Other changes--in the DNA-RNA system, protein biosynthesis, sulphate, energy and other metabolisms--might be secondary. By the character of action vitamin A may be closed to hormones than to water-soluble vitamins.