Lactation

• Areola contains high levels of melanocytes and glands called Montgomery glands which secrete oily lubricant
• Lobules are composed of alveoli which produce milk from alveolar cells. Myoepithelial cells surrounded these and push milk into ducts during feeding
• Oestrogen = increasing proliferation of alveolar and ductal cells

  Progesterone = driving differentiation of cells into alveolar cells
• Inhibition of prolactin is controlled by hypothalamus
• Rising oestrogen and progesterone inhibit dopamine and allow prolactin to rise, but milk is not produced until after delivery
• Mechanosensitive signals from nipple travel to hypothalamus and inhibit dopamine, increasing prolactin and promoting oxytocin
• Oxytocin travels to breast and increases contraction of myoepithelial cells to push milk into ducts
• Breast milk contains insoluble oligosaccharides which are metabolised by the microbiome
• Lactational amenorrhoea is directly related to frequency of suckling and is from altered GnRH and a lack of pre-ovulatory LH surge
• C-sections do not give the same oxytocin rise as vaginal birth so are less likely to breast feed