Question

The cells of the epiblast of a developing mammalian embryo display what cell adhesion molecules on their surfaces, molecules that presumably promote their close association with one another?

Answer 1

The epiblast cells of a developing mammalian embryo display cell adhesion molecules such as cadherins and integrins on their surfaces, promoting close association between cells. Cadherins are involved in forming desmosomes that act as adherens junctions. Integrins bind to ECM proteins, like fibronectin, initiating cell and tissue differentiation signals.

Step-by-step explanation:

The cells of the epiblast of a developing mammalian embryo display a range of cell adhesion molecules on their surfaces that presumably promote their close association with one another. Among these molecules are cadherins, which are integral to the formation of adherens junctions (specifically, desmosomes in epithelial cells). Another key set of cell adhesion molecules are the integrins, which are heterodimeric transmembrane receptors that play a crucial role in cell attachment by binding to extracellular matrix proteins such as fibronectin, laminin, and collagens. Integrins are particularly responsive during embryonic development, helping to signal cell and tissue differentiation through their interaction with the cellular environment.

Additionally, in the context of tissue engineering and wound repair, the incorporation of cell-adhesive peptides that engage integrin receptors, like the oligopeptide Arg-Gly-Asp (RGD), is highly effective in promoting cell attachment to biomaterial scaffolds. This highlights the importance of understanding how these cell adhesion molecules function during early embryonic development, which is crucial for tissue formation and differentiation.

Answer 2

The cells of the epiblast in a developing mammalian embryo mainly express cadherins, which form desmosomes to maintain cell adhesion. Other cell adhesion molecules include integrins that bind to ECM proteins as well as ICAMs such as selectins and NCAMs.

Step-by-step explanation:

Cell Adhesion Molecules in the Developing Mammalian Embryo

The cells of the epiblast of a developing mammalian embryo express certain cell adhesion molecules (CAMs) on their surfaces, which are critical for maintaining their close association with one another. During the complex process of embryogenesis, these cells must adhere properly in order to form tissues and organs. The main cell adhesion molecules involved are cadherins, which are utilized in the formation of desmosomes. Desmosomes function like spot welds that bind adjacent epithelial cells, maintaining the structural integrity especially in tissues that undergo stress, such as skin, heart, and muscles.

Apart from cadherins, another key component of cellular adhesion and communication during embryonic development is the adhesive peptide Arg-Gly-Asp (RGD). RGD, derived from fibronectin, is recognized by several integrins, which are heterodimeric transmembrane receptors. Integrins bind to ECM proteins like fibronectin, laminin, and collagens, establishing connections and facilitating cell signaling for proper tissue differentiation.

Other important CAMs include the Intercellular Cell Adhesion Molecules (ICAMs), which encompass a broad category of adhesion proteins, such as selectins and NCAMs (neural cell adhesion molecules), the latter playing a significant role in neural development. Additionally, markers like CD4 and CD8 found on T cells are also considered cell adhesion molecules that contribute to the effective immune response by maintaining close contact with antigen-presenting cells.