Connective tissue proper is a broad category of tissues with a somewhat loose and flexible matrix. This tissue may be loose which serves as a general packaging material, or dense as it is found in tendons and ligaments. The degree of denseness relates to the concentration of protein fibers versus ground substance in the matrix (loose: the fibers are loosely woven and the ground substance is highly visible; dense: the fibers are densely packed and there is a great predominance of the fibers over the cells and the ground substance).

The fibroblasts are embedded in the matrix; they do not lie in lacunae (chambers within the matrix) as chondrocytes and osteocytes do in cartilage and bone.