Related Experiment Video
Updated: May 31, 2026
07:47
Characterizing Epithelial Wound Healing In Vivo Using the Cnidarian Model Organism Clytia hemisphaerica
Published on: February 10, 2023
Epithelium--the primary building block for metazoan complexity.
1Department of Biological Sciences, University of Maine, 5751 Murray Hall, Orono, Maine 04469-5751.
Integrative and Comparative Biology
|June 18, 2011
Summary
Epithelial cells are fundamental to animal body complexity, arising early in development. Molecular studies reveal conserved mechanisms for epithelial differentiation across diverse species, suggesting a universal evolutionary origin.
Area of Science:
- Developmental Biology
- Cell Biology
- Evolutionary Biology
Background:
- Metazoan body complexity originates from two primary tissue types: epithelium and mesenchyme.
- Epithelium is the default tissue type in Eumetazoa, emerging first in embryonic development.
- Mesenchyme arises from epithelium through the deactivation of epithelial differentiation pathways.
Purpose of the Study:
- To propose a model for the evolutionary origin of epithelia in the stem metazoan.
- To identify conserved molecular mechanisms underlying epithelial differentiation.
- To correlate morphological variations in epithelia with underlying molecular markers.
Main Methods:
- Comparative analysis of epithelial morphology in diverse metazoans.
- Review of molecular studies on epithelial differentiation in model organisms (Drosophila, C. elegans, mouse).
- Extrapolation of findings to reconstruct the evolutionary steps of epithelial development.
Main Results:
- Epithelial differentiation involves conserved molecular steps: establishing cell polarity, cell adhesion via cadherins, forming adherens junctions, creating intercellular gates (septate junctions), and synthesizing a basal lamina with integrin receptors.
- Molecular markers for cell junctions show remarkable similarity across studied metazoan epithelia.
- Despite morphological diversity, fundamental molecular mechanisms of epithelial differentiation are likely universal.
Conclusions:
- Epithelial differentiation follows a conserved molecular pathway, providing a foundation for metazoan body plan evolution.
- The molecular underpinnings of epithelial cell junctions are conserved across Eumetazoa.
- Understanding these conserved mechanisms offers insights into the evolutionary origins of animal tissues.
More Related Videos
Related Concept Videos
01:30Classification of Epithelial Tissues: Simple Epithelium
Simple epithelium consists of a single layer of cells that lines body cavities and blood vessels. The shape of the cells in the epithelium reflects the function of the tissue. Cells in simple squamous epithelium appear as thin scales with flat, elliptical nuclei that mirror the form of the cell.
Because of the thinness of the cells, simple squamous epithelium is present where the rapid passage of chemical compounds is observed. For example, the endothelium that lines the capillaries and vessels...
Because of the thinness of the cells, simple squamous epithelium is present where the rapid passage of chemical compounds is observed. For example, the endothelium that lines the capillaries and vessels...
01:22Classification of Epithelial Tissues: Overview
Epithelial tissues are classified according to the shape of the cells and the number of cell layers formed. Cell shapes can be squamous (flattened and thin), cuboidal (square-like, as wide as it is tall), or columnar (rectangular, taller than it is wide). Additionally, the nucleus shape helps identify the type of epithelial cells. Squamous cells have flattened disc-shaped nuclei, cuboidal cells have spherical nuclei, and columnar cells have elongated nuclei.
Based on the number of cell layers,...
Based on the number of cell layers,...
01:29Classification of Epithelial Tissues: Stratified Epithelium
Stratified epithelium consists of several stacked layers of cells. They provide the durability to withstand constant physical and chemical attacks. Stratified epithelium is named after the shape of the most apical layer of cells. Stratified squamous epithelium is the most common type found in the human body. In this tissue, the apical cells are squamous, whereas the basal layer contains either columnar or cuboidal cells. The basal cells divide to form new daughter cells, which gradually become...
01:23Epithelial Tissues and Their Functions
Epithelial tissues are large sheets of cells covering all of the surfaces of the body. These surfaces can be internal or external, for example, skin, airways, the digestive tract, the urinary system, and the reproductive system. Hollow organs and body cavities that do not connect to the body's exterior, including blood vessels and serous membranes, are lined by epithelial tissue known as the endothelium.
Epithelial tissues provide the body's first line of protection from physical, chemical, and...
Epithelial tissues provide the body's first line of protection from physical, chemical, and...
01:18Tissues
Cells with similar structure and function are grouped into tissues. A group of tissues with a specialized function is called an organ. There are four main types of tissue in vertebrates: epithelial, connective, muscle, and nervous.
01:25Tissues
Tissues are a group of cells that share a common embryonic origin. Microscopic observation reveals that the cells in a tissue share morphological features and are arranged in an orderly pattern to perform specific functions. From an evolutionary perspective, tissues appear in more complex organisms. Although there are many types of cells in the human body, they are organized into four broad categories of tissues: epithelial, connective, muscle, and nervous. Each of these categories is...