Figure 3.

Infiltration of leukocytes and F4/80⁺ cells at the tumor site was reduced in Csf1^op/Csf1^op PyMT mice. (A–D) Primary tumors in PyMT mice at 7 wk of age. Hematoxylin and eosin–stained +/Csf1^op (A) and Csf1^op/Csf1^op (B) tumors (original magnification: ×100). Arrowheads indicate infiltrated leukocytes. The insets in A and B are shown in C and D as adjacent sections immunostained with anti-F4/80 monoclonal antibody (original magnification: ×250). (E and F) Hematoxylin and eosin–stained primary tumors from +/Csf1^op (E) and Csf1^op/Csf1^op (F) PyMT mice at 9 wk. Arrows indicate the site at which the tumor acini adjacent to zones of leukocyte infiltration display disrupted boundaries (original magnification: ×400). (G–J) Primary mammary tumors at late adenocarcinoma stage. (G and H) Hematoxylin and eosin–stained mammary primary tumors; (I and J) adjacent sections immunostained with anti-F4/80 monoclonal antibody from +/Csf1^op and Csf1^op/ Csf1^op PyMT mice at 19 and 20 wk of age, respectively (original magnification: ×250). T, tumor; S, stroma.