Summary
Theoretical reasoning underlying physicochemical measurement of opacity ratio of fibrin
clots, i. e. the ratio of turbidity at 350 nm and 608 nm is given. From such considerations
it is deduced that opacity ratio may be used to characterise clot morphology : opacity
ratio will be inversely related to the size of inhomogeneities formed in the clot.
A highly reproducible technique for the measurement of opacity ratio is described.
Additions of small amounts of dextran to fibrinogen solution consistently decrease
the opacity ratio of clots made subsequently. This decrease which indicates that the
inhomogeneities forming in such fibrin clots are larger than control, is independent
of the molecular weight of dextran, but is related to the logarithm of the final dextran
concentration. Both thrombin and fibrinogen concentrations are also determinants of
opacity ratio. Electron microscopy of fibrin clots made in the presence of dextran
confirms that such clots have an altered morphology. Properties of clots in relationship
to their structural morphology are discussed.