The induction of glutamine synthetase in cell aggregates of embryonic neural retina: correlations with differentation and multicellular organization

A rapid increase in the synthesis and accumulation of the enzyme glutamine synthetase (GS) in the neural retina of the chick embryo characterizes the functional differentiation and maturation of this tissue. A precocious increase of GS can be induced in the embryonic retina by hydrocortisone and related corticosteroids. This paper presents evidence that the responsiveness of neural retina cells to GS induction by the hormonal inducer is dependent on histotypic associations and organization. This was demonstrated, using retina from embryos of different ages, by comparing GS induction in cultures of intact retina tissue with that in aggregates of retina cells and in monolayer cultures of retina cells.