page_title: Egg as food
section_title: Anatomy and characteristics
hierarchical_section_title: Egg as food / Anatomy and characteristics
caption_attribution_description: English: The white eggshell has been removed by dipping a normal chicken egg into vinegar for 48 hrs. Very little retouched.
context_page_description: Eggs are laid by female animals of many different species, including birds, reptiles, amphibians, a few mammals, and fish, and many of these have been eaten by humans for thousands of years. Bird and reptile eggs consist of a protective eggshell, albumen, and vitellus, contained within various thin membranes. The most commonly consumed eggs are chicken eggs. Other poultry eggs including those of duck and quail also are eaten. Fish eggs are called roe and caviar.
  Egg yolks and whole eggs store significant amounts of protein and choline, and are widely used in cookery. Due to their protein content, the United States Department of Agriculture formerly categorized eggs as Meats within the Food Guide Pyramid. Despite the nutritional value of eggs, there are some potential health issues arising from cholesterol content, salmonella contamination, and allergy to egg proteins.
  Chickens and other egg-laying creatures are kept widely throughout the world and mass production of chicken eggs is a global industry. In 2009, an estimated 62.1 million metric tons of eggs were produced worldwide from a total laying flock of approximately 6.4 billion hens.
context_section_description: The shape of an egg resembles a prolate spheroid with one end larger than the other and has cylindrical symmetry along the long axis.
  An egg is surrounded by a thin, hard shell. Thin membranes exist inside the shell. The egg yolk is suspended in the egg white by one or two spiral bands of tissue called the chalazae (from the Greek word χάλαζα, meaning 'hailstone' or 'hard lump').
caption: A raw chicken egg within its membrane, with the shell removed by soaking in vinegar.
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