Figure 2.

Leukocytes are necessary for mammary ductal outgrowth. (a,b) +/Csf1^op mice were irradiated (700 rads, gamma-irradiation) at 19 days of age. A representative mammary gland whole-mount preparation obtained 10 days after irradiation is illustrated (a), in comparison with the nonirradiated control (b). (c,d) +/Csf1^op mice underwent gamma-irradiation (700 rads) at 19 days of age and 2 hours later were (c) or were not (d) given a transplant of a bone marrow cell suspension from +/Csf1^op mice. Representative whole-mount preparations obtained 28 days after irradiation/transplantation (c) and from an irradiated control mouse that did not undergo bone marrow transplantation (d) are shown. Note the restoration of ductal outgrowth after bone marrow transplantation. All the photomicrographs shown are of whole mounts from the entire fourth abdominal mammary gland and were taken at the same magnification. Modified from [7].