Pubertal Mammary Gland Development: Insights from Mouse Models Jillian Howlin & Jean McBryan & Finian Martin Published online: 8 November 2006 # Springer Science + Business Media, Inc. 2006 Abstract During puberty the mammary gland develops from a rudimentary tree to a branched epithelial network of ducts which can support alveolar development and subse- quent milk production during pregnancy and lactation. This process involves growth, proliferation, migration, branch- ing, invasion, apoptosis and above all, tight regulation which allows these processes to take place simultaneously during the course of just a few weeks to create an adult gland. The process is under hormonal control and is thus coordinated with reproductive development. Mouse models, with over- expressed or knocked-out genes, have highlighted a number of pubertal mammary gland phenotypes and given signifi- cant insight into the regulatory mechanisms controlling this period of development. Here we review the published find- ings of the wide range of gene-manipulated mammary mouse models, documenting the common pubertal mammary gland phenotypes observed, and summarizing their contribution to our current understanding of how pubertal mammary gland development occurs. Keywords Mammary gland . Puberty . Terminal end bud . Ductal morphogenesis . Transgenic . Knockout mice Abbreviations TEB terminal end bud FGF fibroblast growth factor PTHrH parathyroid hormone related hormone Bmp bone morphogenetic protein WAP whey acidic protein MMTV murine mammary tumor virus KO knockout ER estrogen receptor PR progesterone receptor GR glucocorticoid receptor VDR vitamin D receptor GHR growth hormone receptor PRL prolactin SRC-1/3 steroid receptor coactivator-1/3 CITED1 Cbp/p300-interacting transactivator with Glu/ Asp-rich carboxy-terminal domain 1 SMAD1/ 3/4 small and mothers against DPP homolog 1/3/4 TGFβ transforming growth factor β IGF-1 insulin like growth factor 1 EGF epidermal growth factor EGFR epidermal growth factor receptor ADAM17 a disintegrin and metalloproteinase domain 17 CSF-1 colony stimulating factor 1 IL-5 interleukin 5 Ntn-1 netrin 1 Neo1 neogenin homolog 1 MMP-2/3 matrix metalloproteinase 2/3 TIMP-1 tissue inhibitor of metalloproteinase 1 ECM extracellular matrix MTA1 metastasis associated 1 J Mammary Gland Biol Neoplasia (2006) 11:283–297 DOI 10.1007/s10911-006-9024-2 J. Howlin : J. McBryan : F. Martin UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland J. Howlin Department of Laboratory Medicine, Clinical Research Centre, Lund University, Cell and Experimental Pathology, Entrance 72, House 91, Floor 11, Malmo University Hospital, S-205 02 Malmo, Sweden F. Martin (*) Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland e-mail: finian.martin@ucd.ie