FIGURE 20-4 Variation in the relative density of cells and ECM in different tissues. (a) Dense connective tissue contains mostly extracellular matrix consisting of tightly packed ECM fibers (pink) interspersed with rows of relatively sparse fibroblasts, the cells that synthesized this ECM (purple). (b) Squamous epithelium viewed from the top, showing epithelial cells tightly packed into a quilt-like pattern with the plasma membranes of adjacent cells close to one another and little ECM between the cells (see also Figure 20-10b).

[Part (a) Biophoto Associates/Science Source. Part (b) Ray Simons/Science Source.]