Sinus repair in the bone marrow of hypoxic mice. Possible relationship to cellular migration.

Observations on the repair of sinus wall in the bone marrow of hypoxic mice are reported. Evidence was found for intravascular coagulation as a mechanism for repair of sinus. Additionally, in both hypoxic and normal mice, strands of fibrin were observed in close association with cells in migration across the sinus wall. We suggest that cells in transit in bone marrow of mice trigger a brief and transient intravascular coagulation phenomena. However, under normal conditions platelets-fibrin clots are not formed and the gaps created by cells in migration are closed by endothelial contraction or by some other mechanism. Large gaps in the sinus of bone marrow which do not close by normal mechanism, may be sealed by solid clots of platelets.