Histology is the study of tissues. Tissues are groups of cells that are similar in structure and function. There are four tissue types associated with animals such as humans. They are:

epithelial_tissue,

connective_tissue (CT),

muscle_tissue, and

nerve_tissue

Each of these tissue categories has distinctive cell shapes and functions.

Connective tissue is the most abundant and variable of the human tissues. It is designed for supporting, protecting, and binding the tissues of the body. Most CT's are well vascularized (except for tendons, ligaments, and cartilage). Connective tissues all consist of three elements: (1) CT cells, (2) matrix produced by the CT cells, and (3) fibers produced by the CT cells. There are many types of cells associated with CT, but the generic "CT precursor cell" is the fibroblast.

Matrix is produced by the CT cells, then released from the cells. It is noncellular and nonliving. It provides extracellular support for the CT cells that produced it. There are several types of fibers in CT. The three major types of fibers are collagen, elastic, and reticular.

NOTE:

(1) Adipose CT is a storage CT, so there is little visible matrix and few visible fibers.

(2) Adipose tissue provides padding, cushions shocks, insulates, and also acts as a "packing tissue" that supports various tissues and organs.

(3) Unless a tissue slide is specifically stained so that the adipose cells pick up dye, they will appear clear.