Cuboidal Epithelial Tissue

and other matter along the surfaces from which they extend. They also act as a barrier, preventing foreign matter from entering these cavities. Squamous Epithelial Tissue Squamous epithelial tissue is composed of thin platelike or scalelike cells forming a mosaic pattern (fig. 1-4). This tissue is found in the tympanic membrane (eardrum) as a single layer of cells, or in the free skin surface in multiple layers. Squamous tissue is the main protective tissue of the body. Cuboidal Epithelial Tissue The cells of cuboidal tissue are cubical in shape (fig. 1-5) and are found in the more highly specialized organs of the body, such as the ovary and the kidney. In the kidneys, cuboidal tissue functions in the secretion and absorption of fluids. CONNECTIVE TISSUE This is the supporting tissue of the various structures of the body. It has many variations and is the most widespread tissue of the body. Connective tissue is highly vascular, surrounds other cells, encases internal organs, sheathes muscles, wraps bones, encloses joints, and provides the supporting framework of the body. Structures of connective tissue differ widely, ranging from delicate tissue-paper membranes to rigid bones. Connective tissue is composed of cells and extracellular materials (materials found outside the cells). Extracellular materials include fibers and the ground substance. The ground substance contains proteins, water, salts, and other diffusible substances. These extracellular materials give connective tissue varying amounts of elasticity and strength, depending on the type of tissue and location. In the following paragraphs we will discuss the three predominant types of connective tissue: areolar, adipose, and osseous. Areolar Connective Tissue Areolar tissue consists of a meshwork of thin fibers that interlace in all directions, giving the tissue both elasticity and tensile strength (fig. 1-6). This type of connective tissue is extensively distributed throughout the body, and its chief function is to bind parts of the body together. Areolar tissue allows a considerable amount of movement to take place because of its elasticity. It is found between muscles and as an outside covering for blood vessels and nerves. The areolar tissue layer connects the blood vessels and nerves to the surrounding structures. 1-4 HM3F0105 Figure 1-5.—Cuboidal epithelial tissue. HM3F0104 Figure 1-4.—Squamous epithelial tissue. HM3F0106 Figure 1-6.—Areolar connective tissue.