This paper studies the effect exerted by TGF-beta1 on the development of chick embryo retina cultured in vitro. The addition of TGF-beta1 to retinal explants inhibited DNA synthesis, measured as 3H-thymidine incorporation into trichloroacetic acid-insoluble fraction, while it increased both wet weight and protein content, in particular that of extracellular matrix proteins. Lastly, in explants treated with TGF-beta1 an increment in the level of fibronectin was demonstrated by means of Western blotting analysis.