Effect of short-term hormone treatment on gland morphology in p53-null transplants. (a,b) Mammary whole mounts were prepared 4 weeks after the removal of hormones in mice from experiment 1A. The ductal organization at the histological and microscopic (hematoxylin/eosin-stained sections, not shown) was similar in the untreated (a) and treated (b) mice (original magnification ×2). (c–f) Whole mounts were prepared at 45 weeks after transplantation in transplants that had not yet developed palpable tumors. A large number of transplants in the untreated group (46%) (original magnifications ×1 (c) and ×2 (d)) and in the treated group (42%) (original magnifications ×1 (e) and ×2 (f)) contained areas of ductal hyperplasias (arrows).