How do you distinguish between epithelium and connective tissue? (give three characteristics)

To distinguish between **epithelium** and **connective tissue**, consider the following three key characteristics: 1. **Cellularity and Cell Arrangement:** - **Epithelium:** Composed of tightly packed cells with minimal extracellular matrix. The cells are closely adherent, forming continuous sheets that cover surfaces and line cavities. - **Connective Tissue:** Contains fewer cells that are scattered within a substantial amount of extracellular matrix. The cells are more loosely organized compared to epithelial cells. 2. **Extracellular Matrix:** - **Epithelium:** Exhibits little to no extracellular matrix. The primary component is the cells themselves, which are bound together by specialized junctions. - **Connective Tissue:** Characterized by a significant extracellular matrix composed of fibers (such as collagen, elastin) and a ground substance. This matrix provides structural support and determines the tissue's properties. 3. **Vascularity (Blood Supply):** - **Epithelium:** Generally avascular, meaning it lacks blood vessels. Nutrients and waste products diffuse to and from epithelial cells via underlying tissues. - **Connective Tissue:** Typically well-vascularized, containing numerous blood vessels that supply nutrients and remove waste. This vascularity supports the diverse functions of connective tissues, such as support, transport, and defense. These distinguishing features help in identifying and understanding the roles of epithelial and connective tissues within the body’s structure and function.