Epithelial Tissue
Closely packed cells with distinct apical and basal surfaces, minimal extracellular material, and visible nuclei; found lining body surfaces and cavities such as the epidermis, digestive tract, and blood vessels.

Connective Tissue
Cells scattered within an extracellular matrix composed of fibers (collagen, elastic, or reticular) and ground substance; found throughout the body providing support, protection, and binding (e.g., bone, cartilage, blood, adipose tissue, tendons).

Muscle Tissue
Elongated, contractile cells that may show striations and multiple nuclei depending on type; found as skeletal muscle attached to bones, cardiac muscle in the heart, and smooth muscle in the walls of organs and blood vessels.

Nervous Tissue
Neurons with a cell body, dendrites, and an axon, supported by glial cells; found in the brain, spinal cord, and peripheral nerves where it transmits electrical signals.