E-learning I

11 important questions on E-learning I

Are the vegetal part and the animal part vem=nly distributed? What is the effect on the cleavage process?

No they are not evenly distributed over the cells, the vegetal half is most contained which causes the cleavage process to slow down.

How is the third cleavage of the embryo formed?

The third cleavage occurs in a plane perpendicular to the first two cleavage planes. The large amount of yaolk material on the vegatl side causes the vlcleavage to move towards the animal pole. This means that the cleavage ends up above the equatorila plane.

Whatis the third cleavage called and why?

It is called the inequal cleavage because it is formed above the equatorial plane.
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Why  does a wavelike motion appear on the egg surface?

Because the cells near the animal part contain less yolk material and thus cleave faster than the cells near the vegetal part.

What is a blastomere?

Daughtercells formed after the first cleavage divisions.

What is the lump of cells formed by cleavages called and what does it look like?

The morula, the cells on the animal side are small and pigmented. The cells on the vegetal side are larger and lack pigment.

When is the embryo referred to as a blastula?

When a fluid-filled cavity called the blastocoel is formed in the animal part of the embryo.

What is the process of epiboly?

When the micromere cap (the wall of the blastula that consists of mutiple layers of cells) moves in the direction of the future blastopore andspreads across the macromere.

What are the three cell migrations characterising the gastrulation?

  1. Epiboly
  2. Involution; influx of cells that will fill the blastocoel
  3. Convergence; many ells move in the direction of the dorsal meridian , to form the dorsal side of the embryo

What are the three germ layers being created in the gastrulation phase?

  1. Ectoderm
  2. Mesoderm
  3. Entoderm

How is the blastopore created?

Through invagination of the cells at the border of the micro- and macromeres in the plane of thesymmetry of the embryo, close to the grey descent the blastopore is created.

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