Lipocyte

These are fat cells that are typically seen as empty spaces in the bone marrow. The amount of non-fat (cellular) portion of the marrow is the marrow's estimated cellularity. Normal cellularity in people between the age of 15 to 75 is expected to be 100 minus the patient's age. Hence, 70% marrow cellularity in a 30 year old patient is the expected norm (100-30=70%). While 70% cellularity in a 75 year old patient is considered a Hypercellular marrow.