Figure 1.

Autoradiographic visualization of E2-induced DNA synthesis in wt (A, C, and E) and Igf1-null (B, D, and F) uteri. A and C and B and D are paired bright- and dark-field low-magnification photomicrographs. E and F are higher magnification dark-field views showing localization of tritium-positive red nuclei in epithelium (ep), stroma (st), and myometrium (my). Mice were given a single intraperitoneal injection of 17-β-estradiol (1 μg/g) at 0 h and injected with [³H]thymidine (2 μCi/g; 1 Ci = 37 GBq) 1 h before sacrifice at 21 h. Sections from the middle third of each uterine horn were exposed to photographic emulsion for 3 weeks, developed, and stained with hematoxylin/eosin and photographed through a red filter. Magnification ×50 (A–D) and ×200 (E and F).