Mammary Gland

The development of breast cancer, the most common malignancy of women, is clearly influenced by environmental factors, particularly during key developing periods or “windows of susceptibility.” With a better understanding of this important interplay, there is heightened awareness and increased implementation of more rigorous methods for hazard identification in in vitro and in vivo models. This chapter provides details about mammary gland biology, development, species comparisons, approaches to hazard identification and study design, morphologic evaluation and diagnosis, and mechanisms of mammary toxicity and carcinogenicity in order to provide necessary background for thorough and appropriate evaluations.