Pierre P. Roger

Control of Proliferation and Differentiation in Primary Cultures of Calf Thyroid Cells

The proliferation of follicular cells and selected gene expression in the thyroid gland in vivo, is mainly controlled by hormones, neurotransmitters, and growth factors either directly or indirectly by means of second messengers (cyclic nucleotides...). Several in vitro thyroid models have been described (1–9). Studies of the effects of different substances on proliferation and differentiation using thyroid cell lines may have little relevance to in vivo situations, whereas data obtained from primary culture of thyroid cells of differing origins often give dissimilar or contradictory results. In addition, the probes available to study thyroglobulin gene expression originate from species different from those used for existing primary cultures. We have, therefore, developed a model consisting of calf follicular cells in primary culture which allows the study of important mechanisms such as proliferation and differentiation, and of the role played by cAMP or growth factors in both processes in vitro. This model gives us the opportunity to use bovine cDNA probes established in our laboratory (10) under conditions of perfect homology with the genetic material used. This will allow a functional and structural study at the molecular level of the thyroglobulin gene expression and of its control promoter in different conditions of stimulation.