Developmental biologyLesson 3 of 5 in the course Embryonic patterning and morphogens

Gastrulation: Germ Layers, Cell Movements, and Developmental Signaling

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Gastrulation reorganizes an early embryo and establishes the foundations for its body plan. This lesson introduces the gastrula, the germ layers, and the movements that help form them.

Gastrulation follows cleavage and the formation of the blastula (or, in mammals, the blastocyst). The early embryo is initially a continuous epithelial sheet. During gastrulation, cells move and rearrange, producing a two- or three-layered embryo called a gastrula. An inward fold or opening associated with this process is the blastopore.

All flashcards

What is gastrulation?
An early developmental process in which the blastula or blastocyst is reorganized into a layered gastrula, establishing germ layers and beginning body-plan organization.
What are the three germ layers in a triploblastic embryo?
Ectoderm, mesoderm, and endoderm: respectively the outer, middle, and inner layers.
What are major ectoderm derivatives?
The epidermis, nervous system, and, in vertebrates, neural crest.
How does ingression differ from invagination?
Ingression is the movement of cells individually from an external layer into the embryo; invagination is the inward folding of a cell layer to make an indentation.
What happens during epiboly?
A cell layer expands and becomes thinner, spreading to enclose deeper layers of the embryo.

Quiz questions

  1. Which cleavage patterns are characteristically associated with protostomes and deuterostomes, respectively?Answer: Spiral, determinate; radial, indeterminate
  2. In Xenopus, what does cortical rotation do before the first cleavage?Answer: Shifts the egg cortex relative to the internal cytoplasm
  3. What is the primary developmental fate of sea urchin primary mesenchyme cells?Answer: Skeletogenic tissue
  4. Which sequence describes Nodal signaling leading to transcriptional support of mesendoderm genes?Answer: Smad2/3 phosphorylation, association with Smad4, and nuclear entry
  5. Which feature can three-dimensional gastruloids model?Answer: Symmetry breaking and axial elongation

Based on the Wikipedia article Gastrulation, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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