Two Kinds of Marrow Fat (IMAGE) Michigan Medicine - University of Michigan Caption The researchers found that both human (left) and rodent (right) leg bones called tibia appear to have two kinds of marrow fat cells, called cMAT and rMAT - and that one tends to concentrate near the top of the bone while the other is lower down. Credit University of Michigan Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.