Microscopic and Macroscopic Structure of Tissue

Abstract

Our understanding of tissue structure comes from an accumulation of knowledge that includes gross and microscopic observations. Gross observations give the biomaterials scientist information about the size, shape, surface, and mechanical properties of a tissue. Light and electron microscopes provide images at low magnification (light microscope 4× to 1000×) and high magnification (electron microscope up to 300,000×). At low magnification, the biomaterials scientist can determine what are the structural units that make up a tissue or organ (Figure 4.1). The structural units usually contain connective tissue and extracellular matrix in some 3-D arrangement that is characteristic to that class of tissue. The connective tissue contains specific cell types; the distribution and type of connective tissue components and cell types are unique for each specific tissue type. At higher magnification in the electron microscope, cell organelles and specific macromolecules can be identified (see Figure 4.1). Because it is the behavior of the macromolecules and their packing arrangement that ultimately dictate how a tissue will behave, it is important to understand the arrangement of specific macromolecules inside cells and in the extracellular environment as well as how structural units fit together to make up gross tissue structure (see Chapter 2).