Insulin and thyroid hormone stimulation of histotypic organogenesis and proteoglycan synthesis in seven-day chick embryo liver.

Livers from seven-day chick embryos were dissociated into single cells and the cells were allowed to aggregate in Dulbecco's Modified Eagle's Medium-12% foetal calf serum, 1-3H-glycosamine, 2-14C-glycine and hormones. Insulin, 10(-6)M, accelerated the rate of aggregation and resulted in larger aggregates than the controls, without added hormone . 3, 3', 5 Tri-iodo-thyronine, 10(-8)M, gave rise to slightly smaller aggregates than control aliquots. Incorporation of 2-14C-glycine and 1-3H-glucosamine was almost linear the first 36 hours whereupon incorporation reached a plateau at 48 hours. Insulin, 10(-6)M, enhanced 1-3H-glucosamine incorporation 54% and glycine incorporation to 42%. Tri-iodo-thyronine stimulated 1-3H-glucosamine 110% and glycine incorporation by 68%. When both insulin and tri-iodo-thyronine were added to the culture medium, glucosamine incorporation was augmented by 156% and glycine incorporation was stimulated by 77%. These findings are interpreted to indicate that synthesis of glycoproteins and proteo-glycosaminylglycans favours histogenesis or specific cell orientation and cell-cell interactions. Hormones had only a small effect on the incorporation of glycine and glycosamine into the soluble media components.