Adjuvant treatment increases neu -induced mammary carcinoma multiplicity. A. Representative histologic section of mammary carcinoma 12 weeks post-infusion, hematoxylin and eosin (H&E) staining, 40× magnification. B. 200× magnification of area defined by box in panel A. C. Rats were injected subcutaneously with 0.5 ml/kg body weight Freund's complete adjuvant (CFA) at 5 (early schedule, n = 15) or 10 (late schedule, n = 15) weeks of age. Booster injections of Freund's incomplete adjuvant (IFA) were given at 7, 9, and 13 (early schedule) or 12 and 14 (late schedule) weeks of age. Controls received saline on the early schedule (n = 14). Rats were palpated weekly for carcinoma development following the infusion of the pJRneu retroviral vector into the mammary ducts at 8 weeks of age and euthanized 9 weeks post-infusion. *P < 0.05 compared with controls, One-Way ANOVA with Bonferroni-Dunn multiple comparisons.