AbstractMicroanatomic injection and corrosion casts were made of 30 human femora of all ages to study the distribution of periosteal and intraosseous arteries; additionally, the marrow of 85 femora (also from all ages) was harvested for histological examination of these vessels. Examination of the diaphyseal and metaphyseal periosteal arteries revealed slight rarefication in density during the lifespan, whereas endosteal arteries were significantly changed in appearance. Two broad dense arterial trees (one located in the proximal half and the other in the distal half) with regular branching crowns were found in the fetal femur. By the second decade of life, the two vascular trees were reduced to an irregular, sparse structure that often showed glomuslike convolutions. Histologically, the intraosseous arteries often developed single or grouped axially oriented smooth muscle cells located in any of the layers of the arterial wall or were sometimes found included within the internal elastic lamina. In about 10% of the glomuslike convolutions, circumscribed intra‐arterial cushions and sphincters of modified epithelioid smooth muscle cells were found. These structures may be part of arteriovenous anastomoses that serve to regulate blood pressure and may release humoral agents. The transformation of the arterial distribution pattern and the occurrence of arterial cushions and sphincters parallel the change of red haematopoetic marrow into yellow marrow. © 1993 Wiley‐Liss, Inc.