Question

attack on titan season 4 release dat plz tell

Answer 1

Answer:

December 7, 2020....

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Answer 2

Explanation:

The chicken (taxon -Gallus gallus) embryo develops and hatches in 20 to 21 days and has been extensively used in embryology studies. Historically, the chicken embryo was one of the first embryos studied, readily available and easy to incubate, embryo development can be directly observed by cutting a small window in the egg shell. A key to this model organism study was the establishment of a staging atlas by Hamburger & Hamilton in 1951[1], which allowed specifc developmental landmarks to be seen and correlated with experimental manipulations of development. This much cited paper included images of all key stages and was more recently republished in the journal Developmental Dynamics (1993), for a new generation of avian researchers. Probably just as important has been the recent chicken genome sequencing, providing a resource to extend our knowledge of this excellent developmental model.

Fertilized eggs can be easily maintained in humidified incubators and during early stages of development the embryo floats on to of the egg yolk that it is using for nutrition. As the embryo grows it sinks into, or below the, yolk. The regular appearance of somites allowed early experimenters to acurately stage the embryo. The embryo was accessible and easy to manipulate (limb grafts/removal etc) that were informative about developmental processes. Chicken cells and tissues (neural ganglia/fragments) are also easy to grow in tissue culture. The discovery that quail cells have a different nuclear appearance meant that transplanted cells (chick/quail chimeras) could be tracked during development. For example, LeDourian's studies showed how neural crest cells migrate widely throughout the embryo.

This collapsible and sortable table compares the chicken incubation period with other bird species.