Adipocyte

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Structure and cellular components of loose connective tissue.

The adipocyte is a connective tissue cell, also known as a fat cell. They differentiate from mesenchymal stem cells. There are two types of adipocytes: white fat cells and brown fat cells.

White fat cells are the most common fat cell type in adults and are unilocular. This means they have a single large lipid droplet with a large diameter and a small amount of cytoplasm. They also have flattened, non-centrally located nuclei. These cells are found in the subcutaneous tissue, omentum and mesentry regions.

Brown fat cells are mulitlocular. This means that each cell has multiple lipid droplets with a smaller diameter than the white lipid cells. These cells have a large amount of cytoplasm and numerous mitochondria that contribute to their color. They also have round, centrally located nuclei. They are more common in new-born babies and are only found in certain regions in adult bodies, like the kidney, aorta and regions of the neck and mediastinum. 

Adipocytes play a role in energy homeostasis. They store excess energy to meet the body's energy demands when the nutrient supply is low. This energy is stored in the form of triglycerides inside the lipid droplets. It is easily released from the adipocytes when needed in other sites of the body.
The adipocyte is specialized to store fat and produce hormones as well as inflammatory mediators and growth factors.

When adipocytes can be found throughout the loose connective tissue as individual cells or in groups. When found in groups or clusters of cells, they are referred to as adipose tissue.