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The chicken embryo is a unique model that overcomes many limitations to studying the biology of cancer in vivo. The chorioallantoic membrane (CAM), a well-vascularized extra-embryonic tissue located underneath the eggshell, has a successful history as a biological platform for the molecular analysis of cancer including viral oncogenesis, [8] carcinogenesis, [9] tumor xenografting, [1] [10] [11 ...
Six commercial chicken eggs — view from the top against a white background. An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the animal hatches.
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'). The shape of a chicken egg resembles a prolate spheroid with one end larger than the other and has cylindrical symmetry along the long axis.
Chickens are featured widely in folklore, religion, literature, and popular culture. The chicken is a sacred animal in many cultures and deeply embedded in belief systems and religious practices. [107] Roosters are sometimes used for divination, a practice called alectryomancy.
As is the case with chickens, various breeds have been developed, selected for egg-laying ability, fast growth, and a well-covered carcase. The most common commercial breed in the United Kingdom and the United States is the Pekin duck , which can lay 200 eggs a year and can reach a weight of 3.5 kg (7 lb 11 oz) in 44 days. [ 34 ]
In 1950, chickens took roughly 16 weeks to reach the ideal weight for sale. Now, chickens are ready to be processed in half that time , thanks to selective breeding and specialized diets.
The egg cell is generally asymmetric, having an animal pole (future ectoderm).It is covered with protective envelopes, with different layers. The first envelope – the one in contact with the membrane of the egg – is made of glycoproteins and is known as the vitelline membrane (zona pellucida in mammals).
Muscle tissue is high in protein, containing all of the essential amino acids, and in most cases is a good source of zinc, vitamin B 12, selenium, phosphorus, niacin, vitamin B 6, choline, riboflavin and iron. [28] Several forms of meat are high in vitamin K. [29] Muscle tissue is very low in carbohydrates and does not contain dietary fiber. [30]