Gastrulation and Embryonic Development

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What is a characteristic of gastrulation in Triploblastics?

Migration of cells from the surface to the interior

What is the result of the migration of cells during gastrulation in Triploblastics?

Formation of the nervous system and skin from the ectoderm

What is the role of microtubules in the cytoskeleton during gastrulation?

To transport elements along the length of the cell

What is the effect of colchicine on the formation of the blastopore lip?

It inhibits the formation of the blastopore lip

What is the significance of the coordination of cellular movements during gastrulation?

It enables the formation of complex body structures

What is the result of the intense metabolic activity during gastrulation?

Synthesis of new proteins

What is the role of the cytoskeleton in cell migration during gastrulation?

It controls the shape of the cell and its movement

What is the characteristic of gastrulation in Diploblastics?

Formation of two germ layers

What is the primary function of glycoproteins in maintaining tissue independence?

To recognize and maintain specific cell-cell interactions

What is the key difference between the embryonic and adult forms of N-CAM?

The embryonic form contains more sialic acid

Which of the following is a characteristic of CAMs?

Independence from calcium

What is the role of the cytoskeleton in relation to CAMs?

It interacts with the cytoplasmic domain of CAMs

During which developmental stage is N-CAM strongly expressed?

Induction of neural tissues

What is the function of the central domain of N-CAM?

It contains sialic acid

What is the main difference between CAMs and Cadherins?

CAMs contain sialic acid, while Cadherins do not

What is the primary function of the amino-terminal domain of N-CAM?

It recognizes other N-CAM molecules

Study Notes

Gastrulation

  • Formation of germ layers: In triploblastic organisms, some cells move inward to form the mesoderm and endoderm, while ectoderm cells remain on the surface to form the skin and nervous system.
  • In diploblastic organisms, such as cnidarians and sponges, only two germ layers are formed.

Cell Movements and Differentiation

  • Gastrulation involves coordinated cell movements, resulting in new cellular associations and interactions.
  • The mesoderm gives rise to reproductive organs, leading to more advanced differentiation.
  • Cell migrations require perfect coordination with other movements occurring simultaneously.
  • Gastrulation is marked by a slowdown in cell division, increased metabolism, and the synthesis of new proteins.

Cytoskeleton and Adhesion Molecules

  • Cytoskeleton plays a crucial role in controlling cell shape and movement during gastrulation.
  • Microtubules orient along the cell's major axis, elongate, and transport cytoplasmic elements.
  • Inhibiting microtubule polymerization, such as with colchicine, prevents cell elongation and formation of the blastopore lip.
  • Actin filaments constriction apical cells.

Adhesion Molecules

  • Cell adhesion molecules (CAMs) and cadherins are essential for maintaining tissue boundaries.
  • CAMs are glycoproteins with homophilic interactions, related to the immunoglobulin superfamily.
  • N-CAM (neural cell adhesion molecule) is a well-known CAM, present in all blastoderm cells, with a 160kD protein chain comprising three domains:
    • Amino-terminal domain with a binding region for other N-CAM molecules.
    • Central domain containing sialic acid, which creates negative charges, weakening interactions between molecules.
    • Carboxyl-terminal domain in contact with the cell membrane.
  • N-CAM is strongly expressed during neural induction, but weakly during cell migration.

Cadherins

  • Cadherins are glycoproteins dependent on calcium, without sialic acid.
  • They are essential for maintaining tissue boundaries and are present in specific forms during embryonic development.

Learn about the process of gastrulation in embryonic development, including the formation of germ layers and their differentiation in triploblastic and diploblastic species.

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