The user provides mice. Mouse islets are then isolated by collagenase digestion. Collagenase P in Hank's buffered saline is directly infused into the pancreas through the bile duct. Groups of two pancreata are then digested in 6.7 mL collagenase P for 6-8 min at 37° using a wrist-action shaker. Depending on mouse strain and genetic modification, islets are either handpicked under microscopic guidance or purified using a histopaque gradient. As part of islet isolation service, the IPA Core provides training for end-users who are interested in islet handling and islet picking.