Brown adipose tissue

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Structure and cellular components of loose connective tissue.

Brown adipose tissue is a specialized type of connective tissue. There are two types: white adipose tissue and brown adipose tissue.

Brown adipose tissue is made up of brown adipocytes. These adipocytes are multilocular, which means that they have a sponge-like appearance, as they have multiple lipid droplets present in their cytoplasm. These adipocytes are arranged in groups or clusters and divided into lobules by connective tissue stroma.

These cells contain numerous mitochondria, small Golgi apparatus, and small amounts of rough endoplasmic reticulum. The large amount of mitochondria within this tissue contains cytochrome oxidase, which gives it its color. Furthermore, the rich supply of capillaries also contributes to its brown color.

Brown adipose tissue is mostly found in newborns. This is because newborns experience extensive heat loss due to their high surface area-to-mass ratio. The metabolism of the brown adipose tissue generates heat in the process of thermogenesis. As the body grows, the amount of brown adipose decreases. In adulthood, it disappears from most sites except the kidney, suprarenal glands, large vessels, and regions of the neck and back as well as the mediastinum.