Gastrulation and Embryonic Development

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Questions and Answers

What is a characteristic of gastrulation in Triploblastics?

Formation of only two germ layers

Increase in the rate of cell division

Differentiation of the ectoderm into the reproductive system

Migration of cells from the surface to the interior (correct)

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

Formation of the nervous system and skin from the ectoderm (correct)

Increased rate of cell division

Formation of only two germ layers

Differentiation of the reproductive system from the ectoderm

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

To transport elements along the length of the cell (correct)

To inhibit cell migration

To provide mechanical support to the cell

To regulate cell division

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

It inhibits the formation of the blastopore lip Signup and view all the answers

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

It enables the formation of complex body structures Signup and view all the answers

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

Synthesis of new proteins Signup and view all the answers

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

It controls the shape of the cell and its movement Signup and view all the answers

What is the characteristic of gastrulation in Diploblastics?

Formation of two germ layers Signup and view all the answers

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

To recognize and maintain specific cell-cell interactions Signup and view all the answers

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

The embryonic form contains more sialic acid Signup and view all the answers

Which of the following is a characteristic of CAMs?

Independence from calcium Signup and view all the answers

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

It interacts with the cytoplasmic domain of CAMs Signup and view all the answers

During which developmental stage is N-CAM strongly expressed?

Induction of neural tissues Signup and view all the answers

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

It contains sialic acid Signup and view all the answers

What is the main difference between CAMs and Cadherins?

CAMs contain sialic acid, while Cadherins do not Signup and view all the answers

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

It recognizes other N-CAM molecules Signup and view all the answers

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.

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Description

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