Definition, object and aims of the avian Anatomy. General characteristics of the body of the birds of the species of veterinary interest. Integumentary system: plumage, skin glands, preen gland. Changes in skin: beak, comb, wattles, feet. Digestive system: oropharyngeal cavity, esophagus, crop, glandular stomach, muscular stomach, intestines and glands, cloaca. Urinary system: kidneys and ureters. reproductive system: testes, ovaries, vas deferens and oviduct, egg-calcium room, egg formation. Respiratory system: nasal cavity, trachea, syringes, lungs, air sacs, pneumatic bones and air circulation.