gastrulation

• What is the main topic discussed in this chapter?

  Gastrulation

  
• What is gastrulation?

  It is an early developmental process where an embryo reorganizes from a blastula into a gastrula.

  
• What does the blastula reorganize into during gastrulation?

  A multilayered and multidimensional structure called the gastrula.

  
• What are the three germ layers formed during gastrulation in poultry?

  The ectoderm, mesoderm, and endoderm.

  
• When does gastrulation start in poultry?

  On the first day of incubation.

  
• What is the primitive streak?

  It is a region of epithelial-mesenchymal transition where epiblast cells ingress to form mesoderm and definitive endoderm.

  
• What are the three blastodermic layers formed during gastrulation?

  Endoderm, mesoderm, and ectoderm.

  
• When does the formation of the three blastodermic layers start?

  At the end of the second week from the primitive streak.
• What follows blastoderm formation in embryonic development?

  Gastrulation.

  
• What is the neural plate?

  A thickened plate of ectoderm along the dorsal midline of the early vertebrate embryo.
• What are the two major ways of forming a neural tube?

  Primary neurulation and secondary neurulation.

  
• How does primary neurulation occur?

  Cells surrounding the neural plate direct the neural plate cells to proliferate, invaginate, and pinch off to form a hollow tube.

  
• What happens during secondary neurulation?

  The neural tube arises from a solid cord of cells that sinks into the embryo and hollows out.

  
• What do the cells at the most dorsal portion of the neural tube become?

  Neural crest cells.

  
• What are some derivatives of the mesoderm?

  Notochord, paraxial mesoderm, intermediate mesoderm, and lateral plate.

  
• What does the notochord give rise to?

  Inductor and intervertebral disc.
• What is the paraxial mesoderm a precursor to?

  The paired somites and somitomeres.
• What does the intermediate mesoderm give rise to?

  Much of the urogenital system, including nephrotome and gonadal cells.
• What does the somatopleura form?

  The outer body wall.
• What does the splanchnopleura develop to produce?

  Internal organs, including sanguineous islets.
• What does the endoderm produce?

  The gastrointestinal tract, annex glands, respiratory system, allantois, and vitelline vesicle.
• What are some derivatives of the mesoderm structures?

  Notochord, paraxial mesoderm, lateral plates, and intermediate mesoderm.

  
• What are the derivatives of the paraxial mesoderm?

  Sclerotome, dermatome, and myotome.
• What does the lateral plate give rise to?

  Somatopleura and splanchnopleura.
• What are the steps in the acquisition of body shape?

  Lengthening of the body, body folding, embryo and annexes separation, tail formation, division of the body in head and trunk, and development of the limbs.
• What is the first step in the acquisition of body shape?

  Lengthening of the body.
• What is the last step in the acquisition of body shape?

  Development of the limbs.
• What does body folding contribute to in embryonic development?

  It contributes to the overall shape and structure of the embryo.
• How does the embryo and annexes separation occur?

  It occurs as part of the acquisition of body shape during development.
• What is tail formation in embryonic development?

  It is a step in the acquisition of body shape where the tail structure begins to develop.

  
• What does the division of the body in head and trunk refer to?

  It refers to a step in the acquisition of body shape during embryonic development.
• What is the significance of limb development in embryonic growth?

  It is a crucial step in the acquisition of body shape and functionality.