Abstract
Summary
The formation of a new sinusoidal marrow in a heterotopic autologous marrow implant requires the intermediation of bone. This conclusion follows from the intimate association of developing marrow tissue and newly formed bone in the implantation site. It has been shown that there is a sigmoidal relationship between the evolution of a medullary cavity and ossicle volume. Moreover, the mean relative medullary cavity size and ossicle volume for each stage of marrow development from hemocytoblasts to a sinusoidal structure conforms to this relationship. Hematopoietic foci emerge during the period of rapid bone resorption. A fully developed marrow may occur in a small or large ossicle provided that the medullary cavity represents a critical fraction of the total volume. It is suggested that processes of bone resorption may contribute to the formation of an appropriate microenvironment and/or provide a source of appropriately modulated progenitor cells. Significantly, bone plays a necessary role in the genesis of an organized marrow in an evacuated medullary cavity as well as in a heterotopic marrow implant.
The authors thank Miss G. Dunn and Mrs. M. Miller for technical assistance.
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