Fig. 2.

TGFβ levels increase in the thymus after birth. (A) Representative IHC sections of thymus from E18.5, day 1, and day 3 neonates stained (Upper) with antibody against active TGFβ1 (positive brown stain with counterstain in blue) and (Lower) H&E. Magnification is 10×. Sections are within five serial sections and are representative of sections from three to four separate mice. (B) Intrathymic amounts of active TGFβ1 were determined by ELISA in E18.5 fetal thymi and day 1, 2, 3, and 4 neonate thymi. Data are representative of two independent experiments with three to seven thymi per time point. (C) Flow cytometric analysis of Smad2/3 phosphorylation in CD4⁺SP thymocytes from day 1, 3, and 5 neonatal thymus (n = 6–7). (D) CD4⁺SP thymocytes were FACS-sorted from day 1–4 neonate thymi, and levels of Smad7 expression were examined by qPCR. Graph shows data from two separate experiments; results are presented relative to day 1. Error bars represent mean ± SEM. *P < 0.05 (unpaired two-tailed Student t test).