Effects of estrogen on hepatic hemopoiesis in the adult mouse.

After a single pharmacologic dose of estriol (E3) treatment, an increase in number of focal areas of hepatic hemopoiesis was observed in adult mice. When syngeneic bone marrow cells were transfused into E3-treated mice, focal hepatic hemopoiesis was increased further. In a single experiment, using a single cell suspension, the concentration of CFUs in the liver was increased 5 days after E3-treatment, while that in the blood decreased. In addition, 51Cr-labeled bone marrow cells selectively accumulated in the E3-treated mouse liver. These results suggest, but in not sense prove, that circulating hemopoietic stem cells are trapped in the E3-treated mouse liver, and that E3-activated Kupffer cells may play a central role in focal hemopoiesis in the liver.