Overview: Hormones and Growth Factors
One of the more exciting areas of developmental biology today is our emerging understanding of the mechanisms whereby development is coordinated between organs. This includes the signals that control breast development and involution, and factors that regulate specific processes relating to lactogenesis. For example, Daniel et al. (Chapter 5) show that transforming growth factor ß (TGF 3) regulates growth and patterning of the mammary ductal tree and is required for alveolar development and functional differentiation. Normal mammary gland development and lactation also requires correct temporal and spatial regulation of apoptosis, and Hadsell and AbdelFatah (Chapter 7) show that such apoptosis, which is activated by the transcription factor AP-1, is inhibited by insulin-like growth factor I.