Marrow

(mar’-o) [AS., mearh, marrow]. 37S MASS The fatty substance contained in the medullarv canal of long bones, and in the interstices of cancellous bone. In early life the marrow of all bones is red (red marrow), but later that within the shafts of long bones a umes atight color (yellow marrow). Red marrow is composed of a delicate reticulum of connective ti ue, containing blood-ve els, large connective-ti ue cells, some of which in growing bone become osteoblasts (marro wcells), giant-cells (myeloplaxes) and red corpuscles in various stages of formation. In yellow marrow most of the cells have been transformed into fat-cells. The function of bone-marrow is probably the formation of red corpuscles. In certain forms of anemia the marrow undergoes profound changes; that of the shafts of the long bones may return to its embryon i cal condition. Bone-marrow has been used in the treatment of pernicious ir.enna. 380