Opossums: New World marsupials of the family Didelphidae. Opossums are omnivorous, largely nocturnal and arboreal MAMMALS, grow to about three feet in length, including the scaly prehensile tail, and have an abdominal pouch in which the young are carried at birth.Monodelphis: A genus of short-tailed OPOSSUMS in the family Didelphidae found in South American, chiefly Brazil. They are opossums least well-adapted to arboreal life.Didelphis: A genus of large OPOSSUMS in the family Didelphidae, found in the Americas. The species Didelphis virginiana is prominent in North America.Marsupialia: An infraclass of MAMMALS, also called Metatheria, where the young are born at an early stage of development and continue to develop in a pouch (marsupium). In contrast to Eutheria (placentals), marsupials have an incomplete PLACENTA.Sodium-Phosphate Cotransporter Proteins: A family of symporters that facilitate sodium-dependent membrane transport of phosphate.Macropodidae: A family of herbivorous leaping MAMMALS of Australia, New Guinea, and adjacent islands. Members include kangaroos, wallabies, quokkas, and wallaroos.Kidney Tubules, Proximal: The renal tubule portion that extends from the BOWMAN CAPSULE in the KIDNEY CORTEX into the KIDNEY MEDULLA. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the U-shaped LOOP OF HENLE.Esophagus: The muscular membranous segment between the PHARYNX and the STOMACH in the UPPER GASTROINTESTINAL TRACT.