Fig. 4.

Pax8 controls expression of Bcl2 and apoptosis in the thyroid. A–C. In Pax8 heterozygous embryos, expression of Nkx2-1 and Bcl2 transcripts (A, B) as well as Bcl2 protein (C) is abundant. D–F. Whereas Nkx2-1 transcripts (D) are unaffected in Pax8 deficient embryos, levels of Bcl-2 transcripts (E) and protein (F) are strongly downregulated. G, H. In contrast to control embryos (G), scattered caspase-3 positive cells are seen in the thyroid bud of E11.5 Pax8 deficient embryos (H). I, J. In newborn mice TUNEL positive apoptotic cells are absent in control pups (I) but abundant in the thyroid gland when Pax8 has been conditionally deleted (J). Sagittal sections. Scale bar = 75 μm.