Colony-stimulating factor (CSF) in oestrogen-stimulated spayed murine uteri

A form of colony-stimulating factor (CSF) is known to be present in extracts of the uteri of normal mice. In this study CSF was not found in extracts of the uteri of untreated spayed mice but was present in uteri of these mice treated with oestradiol. CSF could be detected 9 h after oestradiol-administration. The occurrence of CSF in the uteri of spayed mice treated with oestradiol did not require DNA synthesis. The same amount was detected in uterine extracts whether or not DNA synthesis of the oestradiol-treated spayed mice had been prevented by hydroxyurea.