Read the summary and the most important questions on Mens- en dierkunde1

• Thema 1: H3+H4 part 1

  This is a preview. There are 14 more flashcards available for chapter 14/03/2015
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• What is a blastomere?

  Blastomere is a large cluster of small cells formed during cleavage

• Which pole is the animal pole and which is the vegetal pole?

  yolk rich = vegetal
  other end = animal

• What does isolecithal egg mean?

  Iso=equal. Eggs with little yolk that is evenly distributed. 

• what is an mesolecithal egg?

  meso=middle. Egg with moderate amount of yolk at vegetal pole

• What is invagination and what does it form?

  invagination is when 1 side of the blastula bends inwards. This forms a new cavity called gastrocoel, archenteron or oerdarm.

• What is a blastopore?

  opening to the gut where invagination began.

• Describe the 2 ways in which mesoderm can be formed?

  1. Schizocoely: cells arise from ventral area near blastophore lip and spread into space between archenteron and outer cell wall. --> protostomes
  2. Enterocoely: central region of archenteron wall puches outward into space between archenteron and outer body wall. --> deuterostomes

• What is the primary organizer and why?

  The dorsal lip, because it is the only tissue capable of inducing development of a secondary embryo in the host.

• What is epigenesis? And what are its 3 steps?

  view that an embryo develops and differentiates step by step from a zygote undergoing cell division. 
  

  1. pattern formation
  2. determination of positions in the body
  3. induction of limbs and organs appropriate for that position

• Thema 1: H3+H4 part 2

  This is a preview. There are 25 more flashcards available for chapter 15/03/2015
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• What is sonic hedgehog and what does it do?

  sonic hedgehog is secreted from the ZPA (zone of polarizing activity) and establishes the anteroposterior axis and it assusres that fingers/toes develop in appropriate order.