White and Brown Adipose Depot Collection from Mouse Pup: A Surgical Procedure to Harvest the White Adipose Tissue and Brown Adipose Tissue from Mouse Pup

In mammals, adipose tissue or fat depot - a specialized connective tissue composed mainly of fat cells or adipocytes can be divided into two major types - white adipose tissue or WAT and brown adipose tissue or BAT.

The WAT consists of white adipocytes with few mitochondria and single lipid droplet, and stores energy. The major WATs are the subcutaneous inguinal WAT and visceral WAT.

The BAT comprises brown adipocytes with numerous mitochondria and lipid droplets and regulates body temperature. This tissue can be found in the interscapular, cervical, and axillary regions.

To isolate these adipose tissues, begin with a euthanized mouse pup in the left lateral position. Next, make an incision on the abdominal skin. Gently retract the skin towards the limbs.

Identify the subcutaneous WAT located within the innermost layer of skin, anterior to the upper segment of the hind limbs. Carefully excise the thin, elongated subcutaneous WAT from underneath the skin.

Now, position the mouse pup in the prone position. Incise the dorsal skin from the shoulder blade or the interscapular region towards the head. Locate the interscapular BAT - the deep red tissue between the shoulder blades. Gently remove the interscapular BAT.

Wash the harvested adipose tissues with a suitable chilled buffer. Store the adipose tissues in tubes containing buffer at low temperatures until further processing.