Fig. 1. Whole-mount analysis of inguinal mammary glands from normal and early stages in tumorigenesis at different hormonal conditions. Whole mount of virgin normal mammary gland (A), EL11 ductal outgrowth (B), and TM2L alveolar outgrowth (C) were analyzed at control, ovariectomized (OVX), and pituitary isograft-stimulated (+Pit) states. Hormone deprivation by ovariectomy in A–C exhibited differences in branching morphogenesis only in virgin and EL11 ductal outgrowths but not in TM2L alveolar outgrowths. Stimulation by pituitary isograft resulted in a striking difference in alveolar development between virgin gland (A) and EL11 outgrowth (B). Arrows, the most prominent features in each group at a specific hormonal status. Bar, 5 mm. The image on the left of each whole mount is an equal enlarged portion of the mammary gland on the right.