Here are five adaptations of the placenta to its function: 1. Large surface area: The placenta has numerous, highly folded chorionic villi. This extensive folding and branching significantly increases the surface area available for the efficient exchange of nutrients, oxygen, and waste products between the maternal and fetal blood. 2. Thin barrier: The barrier between the maternal and fetal blood (consisting of the chorionic villi epithelium and fetal capillary endothelium) is extremely thin. This minimizes the diffusion distance, allowing for rapid and efficient transfer of substances. 3. Rich blood supply: Both the maternal and fetal sides of the placenta have an extensive network of blood vessels. This ensures a constant supply of oxygen and nutrients to the fetus and efficient removal of carbon dioxide and metabolic wastes, maintaining steep concentration gradients for diffusion. 4. Selective permeability: The placental barrier is selectively permeable, allowing essential substances like glucose, amino acids, vitamins, minerals, oxygen, and antibodies to pass from mother to fetus, while generally preventing the passage of larger, harmful molecules and maternal blood cells. 5. Hormone production: The placenta acts as an endocrine organ, producing vital hormones such as progesterone and estrogen. These hormones are crucial for maintaining the uterine lining, preventing premature uterine contractions, and preparing the mother's body for childbirth and lactation.