Gastrulation and Embryonic Tissue Origins

22 Questions

Which process involves cells reorganizing to form less layers allowing the cells to extend out from a point?

Convergent Extension

Which germ layer forms the epithelial linings of the respiratory and digestive tracts, including the glandular cells of the liver and pancreas?

Endoderm

Which structure is formed from the mesoderm?

Liver stroma

Which process involves a tissue layer folding in or out?

Invagination (Evagination)

Which germ layer gives rise to the central nervous system and peripheral nervous system?

Ectoderm

Which structure is NOT formed from the mesoderm?

Blood

Which process occurs during gastrulation?

Formation of the primitive streak and the notochord

What are the three tissue layers produced by gastrulation called?

Embryonic germ layers

Which layer forms the outer layer of the gastrula?

Ectoderm

What lines the embryonic digestive tract?

Endoderm

What is the process by which the bilaminar embryonic disc is turned into the trilaminar embryonic disc?

Gastrulation

What is an important process occurring during gastrulation besides formation of the primitive streak?

Formation of the notochord

During which week of development does the primitive streak form?

Second week

What does the notochord act as during embryo development?

Rigid axis for the embryo

What happens to the process of forming mesoderm through the primitive streak after the second week?

Slows down and degenerates in the sacrococcygeal region

What are oropharyngeal membrane and cloacal membrane examples of during embryonic development?

Faint depressions that appear in the ectoderm

What is the role of the primitive streak during gastrulation?

Defining the body axis and leading to notochord formation

Which movement involves layers separating as sheets during embryonic development?

Delamination

What is formed by invagination of cells from the primitive pit?

Notochordal canal and notochord

What does gastrulation lead to in terms of cell migration?

Migration to form all three germ layers

What is the function of mesoderm in embryonic development?

Contributing to muscle and reproductive system development

Which structure serves as a foundation for the vertebral column?

Notochord

Study Notes

The mesoderm is a layer of cells that partly fills the space between the endoderm and ectoderm, contributing to the development of muscles and the reproductive system.
During the third week of development, a thickened linear band of epiblast on the dorsal caudal aspect of the embryonic disc forms, leading to the development of the primitive node, primitive pit, and primitive groove.
The process of forming mesoderm through the primitive streak slows down after the second week and degenerates in the sacrococcygeal region of the embryo.
The oropharyngeal membrane and cloacal membrane are two faint depressions that appear in the ectoderm during the third week.
The notochordal process elongates by invagination of cells from the primitive pit, forming a notochordal canal and a notochord.
The notochord is a key structure that acts as a rigid axis around which the embryo develops, serving as a foundation for the vertebral column and inducing the formation of the neural tube (future nervous system).
During development, cells undergo various movements and rearrangements, including ingression (cells breaking away as individuals), delamination (layers separating as sheets), and intercalation (layers connecting with each other).
Gastrulation begins when cells of the epiblast migrate to the median plane of the dorsum of the embryonic disc, with the primitive streak defining the body axis (rostrocaudal and left-right) and leading to the formation of the notochord.

Test your knowledge of gastrulation and embryonic tissue origins with this quiz. Identify the embryological differences of gastrulation and learn about the origins of various embryonic tissues.

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