Figure 5.

Photomicrographs showing mammary gland wholemounts from parous rats treated with insulin-like growth factor (IGF)-I (upper row, panel a; lower row, panel a), untreated parous rats (upper row, panel b; lower row, panel b), and age-matched virgin rats (upper row, panel c; lower row, panel c). The IGF-I treatment (0.66 mg/kg body weight/day) was continued for 7 days before the animals were killed and the wholemounts were prepared. Note the smaller alveolar structures of the mammary epithelia from parous animals, particularly untreated parous rats, as compared with the age-matched virgin rats (upper row of panels) and the presence of terminal end-buds in the mammary glands from all groups (lower row of panels). Magnifications: 6.25× (upper row) and 10× (lower row).