Most Things Biology

Adipose CT

Time To Read

2–4 minutes

Date Last Modified

Adipose connective tissue is commonly known as adipose tissue or fat tissue. It is a specialized type of connective tissue. It is primarily composed of adipocytes. These cells are specialized in storing energy in the form of triglycerides (fat). 

Microscopic view of Adipose connective tissue, slide 177-2, from a recto anal junction. Staining highlights the cellular structure: large, polygonal adipocytes with clear cytoplasm and peripheral nuclei. Thin fibrous septa separate the cells. Connective tissue is visible in the upper-left corner.
Figure 1: Adipose connective tissue from a recto anal junction.

View the Slide Yourself

Access this slide from the Histology Guide:
https://www.histologyguide.com/slideview/VH-010-brown-fat/03-slide-1.html?x=15873&y=18316&z=22.877
The purple tab on the right opens a panel with information and links.

Cells

 Adipocytes are the primary cell type found in adipose tissue. They are tightly packed together. Very little matrix can be seen between the cells. (Remember that the designation as a loose or dense connective tissue comes from the packing of the fibers, not the cells.)  These cells appear “hollow” but they are not.  An oil droplet of stored triglycerides occupies the majority of the space in these cells.  With the common H&E stain, the cell membranes and nuclei take up the stain, but the triglyceride droplet does not.  The cell membranes of adipose cells usually has a wavy appearance to it.  The darkly-stained nuclei are pushed against the cell membrane. This occurs in an attempt to make more room for the oil droplet.  

Fibers

Collagen fibers provide tensile strength and structural support to the tissue. Reticular fibers are sometimes found within the tissue.

Matrix

The ground substance of adipose tissue is composed of glycosaminoglycans (GAGs), proteoglycans, and water. It fills the spaces between cells and fibers, providing support and maintaining tissue hydration and homeostasis.  Adipose tissue is lipid-based. It does not hold the same amount of water per volume as muscular tissue and other connective tissues.  The balance between adipose and non-adipose deposits on the body can significantly impact hydration. It also influences conditions such as heat stroke.  

Functions

Adipose tissue stores excess energy in the form of triglycerides. When the body needs energy, these triglycerides are broken down into fatty acids and glycerol. Various tissues and organs use these as fuel. Adipose tissue acts as an insulating layer, helping to regulate body temperature by providing thermal insulation. It helps to prevent heat loss from the body and maintains internal temperature stability.  Adipose tissue cushions and protects vital organs from mechanical shocks and trauma. It acts as a protective padding around organs such as the kidneys and the eyes, reducing the risk of injury.

High-magnification light microscopy image of adipose tissue. The field of view is filled with large, rounded adipocytes distinguished by their pale, translucent cytoplasm and thin, pink-stained cell membranes. The extracellular matrix, stained in varying shades of red, is visible between the adipocytes, revealing connective tissue components. The composition highlights cellular detail and tissue architecture.
Figure 2: Adipose tissue microphotograph showing large, round adipocytes with visible cell membranes stained in pink and red.
Micrograph of adipose tissue stained with H&E. Adipocytes appear as large, circular, clear spaces due to lipid washout during preparation. Thin pink stained cell membranes define each adipocyte. Interstitial space contains nuclei and scant connective tissue, also stained pink.
Figure 3: Adipose tissue (fat) cells under a microscope.
Histological micrograph of adipose tissue (mesentery). Numerous adipocytes with large, clear intracellular lipid droplets and peripherally located, dark-staining nuclei. The cytoplasm is sparse and thin. Connective tissue stains pink and borders the cells. Hematoxylin and eosin staining. High magnification.
Figure 4: Adipose tissue histology showing fat cells with peripheral nuclei, stained pink.

Locations

Subcutaneous adipose tissue is located beneath the cutaneous membrane (your skin). It serves as insulation and as a source of energy. Subcutaneous fat is distributed all over the body. It tends to accumulate in certain areas, such as the abdomen, buttocks, thighs, and upper arms. Visceral fat is found around internal organs within the abdominal cavity, including the liver, intestines, and kidneys. It cushions and protects these organs and provides a source of energy. Adipose tissue is also found within bone marrow. In this location, it serves various functions. These functions include a last-resort energy storage and support for hematopoiesis (blood cell production).

Easily Confused With

Dense Irregular, Elastic Cartilage

Figure 1: Recto-anal junction, monkey, H&E, 40X Slide 177
Figure 2: Mesentery, H&E, 40X Slide 042
Figure 3: Thick skin, sole of foot, H&E, 40X Slide 106
Figure 4: Mesentery, H&E, 40X Slide 030
All by University of Michigan Histology, licensed under CC BY-NC-SA 3.0.

Explore More on Connective Tissues Histology

<Back to the Connective Tissues Main Page

Link to more on Connective Tissues Histology

General Information
Adipose CT
Areolar CT
Reticular CT
Dense Regular CT
Dense Irregular CT
Elastic CT
Bone CT
Hyaline Cartilage CT
Elastic Cartilage CT
Fibrocartilage CT

List of terms