Kimby Barton, BSc, MSc
Assistant Editor, Geriatrics & Aging

The hematopoietic system is comprised of all the elements of the blood, together with the stem and progenitor cells that give rise to these elements, and these play a vital role in the functioning of a healthy person. The hematopoietic system is unusual in that most of its components have a short life span, a multiplicity of cell types are required for its normal function, and a wide dispersion of cells perform specific functions throughout the body. The short life span of many of its components renders necessary the continuous production of enormous numbers of cells. Consequently, stem and progenitor cells must be maintained in adequate numbers to meet this demand for cell production throughout a person's lifetime.

Age-related alterations have been found in almost all components of the hematopoietic system but historically it has been difficult to distinguish between changes that occur with advanced age and changes that occur as a result of an illness. This article will review some of the literature dealing with the effects of age on the hematopoietic system. Conflicting studies will leave some questions unanswered and a paucity of information in other areas suggests the need for further research.