Figure 2.

Epigenetic effect of RTHβ and its transgenerational inheritance across the male line. Individuals were given 25 µg L-T₃ twice daily for three days. They were then injected intravenously with 200 µg of thyrotropin releasing hormone (TRH) and samples of blood were obtained at the indicated times for the measurement of serum TSH. Plotted on the graphs are results from female (circles) and males (squares). Increased peak responses in (A, C, D), as compared to those of (B, E) indicate reduced sensitivity to thyroid hormone (RSTH). While this epigenetic effect of exposure to high TH levels during fetal life (A) is transmitted to both sexes, it is inherited along male line only (C, D) but not the female line (E).