The intricate development and physiological dynamics of the mammary glands, orchestrated by a delicate interplay of hormones, are crucial for reproductive function and lactation. Beginning with intrauterine clusters evolving into mature glands, hormonal fluctuations throughout puberty and the menstrual cycle finely tune mammary tissue growth. Oestrogens stimulate the proliferation of epithelial cells, while progesterone orchestrates the formation of lactiferous glands. During pregnancy, oestrogen and progesterone induces hyperplasia of lobules and ducts, preparing the breast for lactation. Prolactin is vital for lactation and stimulates milk production during pregnancy and postpartum. As shown by ultrasonography, physiological changes during lactation reflect glandular tissue transformation for milk secretion. Clinical and physiological changes, including increased blood flow, contribute to mammary growth and firmness, complicating clinical examination. Ultrasonographic findings reveal variability in women’s glandular and fat tissue distribution, suggesting that milk production is not solely determined by anatomical factors. Though not directly linked to milk production, blood flow dynamics hint at a threshold for optimal lactation. Understanding these complex hormonal and physiological mechanisms is crucial for comprehending mammary development, function, and clinical assessment.