Figure 4.

Thyroid gland function assessed by [¹²⁵]I uptake. (A) Developmental series in days postfertilization. (B) Goitrogens and/or 20nM T₄ added on day 4 and radioiodide uptake on day 24. Lanes: 1, control; 2, 1 mM methimazole; 3, 1 mM methimazole and 20 nM T₄; 4, 20 nM T₄; and 5, 1 mM methimazole until day 12 then control until day 24. (C) Four different goitrogens were added at day 12 postfertilization; radioiodide uptake was assayed on day 33. Inhibitor concentrations were: 0.005% 6-n-propyl-2-thiouracil, 0.003% TU, 0.05% KClO₄, and 0.3 mM methimazole.