Adipose Tissue – Tutorial

Please read Unit 2 – Introduction to Connective Tissues prior to completing the activities in this chapter.

Introduction to Adipose Tissue

Adipose (fat) tissue is a type of connective tissue proper composed almost entirely of adipocytes (fat cells) with very little extracellular matrix between cells.  Individual adipocytes contain large volumes of stored lipids (triglycerides) causing the cell’s nucleus, organelles, and most of the cytoplasm to get pushed to one side of the cell.  Adipocytes continually adjust their stored fat content based on the metabolic needs of the body.  When food is scarce or metabolic fuel demands are high, adipocytes can break down stored triglycerides and release fatty acids into the blood which can be used as an energy source for cells of the body.  When this occurs, an adipocyte essentially collapses as the volume of stored lipids decreases.   When calories are plentiful and metabolic demands of the body are low, adipocytes can remove circulating fatty acids from the blood and store them as triglycerides causing the adipocyte to increase in size.  However, fat cells cannot divide by mitosis and adipocytes can’t increase in volume indefinitely, so If circulating lipid levels remain chronically elevated, mesenchymal cells (connective tissue stem cells) will divide and differentiate into new adipocytes to store more fat.

Since adipocytes are “soft and squishy” when filled with fat and have very little water content for the volume of the cell, adipose tissue serves to cushion or pad delicate structures and acts as insulation to help prevent heat loss in addition to its primary function of energy storage.  Therefore, adipose tissue is found primarily in the hypodermis of the skin (under the skin) where it can provide padding and insulation.  Adipose is also concentrated behind the eyes and around the kidneys where it provides a cushioning effect.  Adipose is also common under the mesothelial linings, especially around the heart (pericardium) and in the greater omentum of the abdominal cavity.  It should also be noted that adipose cells are also found in areolar tissue so large volumes of adipose can be found in areolar tissue in locations all over the body (especially in the sheath around blood vessels and nerves) in individuals with high levels of body fat.

Tutorial:  Use the image slider below to learn more about the characteristics of adipose tissue. 

Microscopy:  Use the image slider below to learn how to use a microscope to identify and study adipose tissue on a microscope slide of human skin (from the scalp).

Tutorial:  Use the hotspot image below to learn more about the characteristics of adipose tissue. 

Tutorial:  Use the image slider below to study numerous examples of adipose tissue.