On the question of the transformation of fibrin into fibrous tissue in tissue culture preparations

During the past year there appeared a paper by Baitsell 1 working in Professor Harrison's laboratory at Yale University describing changes in the fibrin clot of tissue culture preparations, which he interpreted as a transformation of the fibrin meshwork into fibrous tissue. Extending his observation to the living animal this author has described 2 in the healing wounds of frogs similar changes in the fibrin which early fills the wound and concludes that instead of forming a temporary scaffolding to be removed later, the fibrin becomes transformed into permanent collagen fibrils such as are found in the healed scar. This view is so at variance with that generally held that a careful review of the work seems desirable.

The changes in the fibrin referred to may be briefly described. When the tissue culture is first prepared the fibrin meshwork of the clot is so delicate that the coagulum appears as a homogeneous almost translucent mass. Within two to five days as the clot contracts there appear in a certain number of the preparations, coarse fibrils sometimes wavy in character which radiate generally from the central fragment of tissue. We have observed this change in clotted fowl, human and rabbit plasma, as well as in frog plasma studied by Baitsell. The formation of these coarse fibrils is evidently the result of the contraction of the clot with fusion of many of the delicate fibrin threads. The change may be facilitated, as Baitsell has pointed out, by mechanical disturbances such as loosening of the clot at certain points. In human pathological material one sees a similar formation of coarse fibrils wherever fibrin in any quantity is deposited as for example, in fibrinous pleurisy, peritonitis, thrombi, pneumonic exudate, etc.