Molecular Regulatory Mechanisms of Mammary Gland Development: A Review.

Mammary gland development represents a complex and highly regulated biological process that is critical for mammalian reproductive success. This review provides a comprehensive analysis of the molecular, cellular, and hormonal mechanisms governing mammary gland development across distinct developmental stages: embryonic, pubertal, pregnancy, lactation, and involution. Mammary organogenesis is orchestrated by multiple factors, including conserved genetic pathways, endocrine signaling cascades, and environmental stimuli. Drawing primarily from studies in rodents and dairy ruminants, recent advances in molecular biology have elucidated key signaling pathways, including Wnt, Notch, and TGF-β, which provide fundamental insights into mammary epithelial growth and differentiation. Furthermore, we examine the effects of external factors, including thermal stress, photoperiodic variation, and dry period duration on mammary function and lactational performance. The dry period, in particular, serves a critical role in tissue remodeling and preparation for subsequent lactation cycles. Through systematic review of physiological and molecular dynamics across developmental stages, this article identifies key genetic regulators and cellular mechanisms, offering valuable insights for optimizing milk production and composition in agricultural systems.