Cell ingression

Definition

Cell ingression is a biological process during which individual cells move from a tissue layer into the interior of an embryo, often resulting in the formation of new cell populations. This movement is crucial during early developmental stages, particularly during gastrulation, where cells transition from an epithelial state to a mesenchymal state, allowing them to migrate freely. This process contributes significantly to the establishment of germ layers and the overall architecture of the developing embryo.

5 Must Know Facts For Your Next Test

1. Cell ingression occurs primarily during gastrulation and is essential for forming the mesoderm layer.
2. The process involves changes in cell shape and adhesion properties, allowing cells to detach from their neighbors and migrate inward.
3. Cell ingression is influenced by signaling pathways such as Wnt and FGF (Fibroblast Growth Factor), which help regulate cell behavior during development.
4. Ingression contributes to the organization of tissues by allowing cells to position themselves appropriately within the developing embryo.
5. This process can be observed in various model organisms, including amphibians like Xenopus laevis and mammals like mice.

Review Questions

• How does cell ingression contribute to the formation of germ layers during embryonic development?
  • Cell ingression is a vital mechanism that allows individual cells to move from the outer layer of the embryo into its interior, facilitating the formation of germ layers. During gastrulation, cells that ingress contribute primarily to the mesoderm layer while other layers such as ectoderm and endoderm are formed through different movements. The rearrangement of cells through ingression helps establish the body plan and contributes to the overall organization of tissues in the developing embryo.
• Compare and contrast cell ingression with other mechanisms of cell movement during embryogenesis, such as involution and epiboly.
  • Cell ingression differs from involution and epiboly in how cells move during embryogenesis. While ingression involves individual cells detaching from an epithelial layer to migrate inward, involution refers to layers of cells rolling inward to form new layers. Epiboly describes the expansion of one cell layer over another, typically seen when ectodermal cells spread over the yolk. Each mechanism plays a unique role in shaping the embryo and forming its different tissue layers.
• Evaluate the importance of signaling pathways in regulating cell ingression during gastrulation and their implications for developmental biology.
  • Signaling pathways such as Wnt and FGF are crucial for regulating cell ingression during gastrulation by influencing cellular behavior, such as motility and adhesion. These pathways activate genes that promote epithelial-to-mesenchymal transition (EMT), allowing cells to change shape and migrate into the embryo. Understanding these pathways not only sheds light on normal developmental processes but also has implications for studying diseases like cancer, where similar mechanisms can lead to metastasis.

Related terms

Gastrulation: A phase in early embryonic development where the single-layered blastula reorganizes into a multilayered structure, forming the three primary germ layers: ectoderm, mesoderm, and endoderm.

Epithelial-to-mesenchymal transition (EMT): A biological process where epithelial cells lose their cell polarity and cell-cell adhesion properties, acquiring migratory and invasive traits to become mesenchymal stem cells.

Mesoderm: One of the three primary germ layers formed during gastrulation, which gives rise to muscles, bones, and other internal structures.