[Vitamin A--a probe in the study of growth, differentiation and morphogenesis].

Scientific work on vitamin A research has started more than one hundred years ago. The information accumulated thus far has already been published in thousands of original papers, review articles, monographic series and books. The overall result of these investigations can be concentrated in the title of the present review. Vitamin A and its analogues, the retinoids, participate directly in several physiological functions, such as vision, growth, development and differentiation. These compounds have also found useful application in the cure of several serious dermatological diseases and in cancer therapy. Their activities are also widely exploited to study embryogenesis, teratogenesis and carcinogenesis. Recent advances ascribe to retinoic acid properties, which render it a putative candidate for the first vertebrate morphogen. These developments, in combination with progress made in the study of homeo box genes, open new ways towards elucidating the mode of action of retinoids at the molecular level. It is tempting to speculate that, understanding enough about the basic biology of retinoid action, might be beneficially exploited for the betterment of the mankind.