[The biological bases of human lactation]

The mammary gland integrated by secretory acini has two main physiological goals: the lactogenesis and the milk ejection. The first is controlled by estrogens, prolactin and cortisol; the former by oxytocin. Milk is synthesized through five mechanisms namely: I. Cellular synthesis and exocytosis; 2. Cellular synthesis and exocytosis packed in cell membrane fragment; 3. Passive transport through both cell membranes; 4. Active transport via receptors through both cell membranes, and 5. Paracellular transport. The human milk has a high concentration of lactose and relatively low concentrations of fat and protein in comparison to other species. Its composition varies little in relationship to maternal diet, nevertheless, it holds a close correlation, with body composition of the mother. Exclusively breast-fed infants grow in a similar manner to those formula-fed up to 4-6 months; afterwards growth decelerates, to spurt up the need for complementary food. It has been amply demonstrated that human milk protects against acute infections, both bacterial and viral. The current hospital practices of perinatal care should be changed in our country in order to favour the initiation of breast-feeding. Concerned physicians should have more and precise knowledge about the physiology of lactation in order to help mothers to pursue a successful lactation.