Suspension culture reveals a morphogenetic property of a thyroid epithelial cell line.

It is known that freshly dissociated thyroid cell clusters form follicles in suspension culture. Thyroid epithelial cell lines, grown for many generations in vitro, fail to show colloid-containing lumina when cultured as monolayers. Several thyroid cell lines, some transformed, have been tested with respect to their ability to form extracellular lumina when transferred from monolayer to suspension culture. One cell line in particular, the T78 cell line, showed this property when cultured in suspension. Lumina formed within 3 days even in the absence of added thyrotropin (TSH). The ultrastructure of lumina within cell aggregates resembled that of the thyroid follicle in vivo. The ability to undergo morphogenesis may therefore be an intrinsic property of thyroid epithelial cells which is retained for a large number of generations in vitro and is revealed by proper culture conditions. The shift from monolayer to suspension culture may thus lead to the expression of a thyroid differentiated function such as the formation of follicle-like structures.