[Age-dependency of toluidine-blue dichroism and birefringence of fibers within the costo-chondral junction of human ribs (author's transl)].

The chondral fibers running parallel to the chondrocyte columns within die costo-chondral junction of human ribs were investigated quantitatively following standardized Toluidine blue staining by using the Leitz-Mikrospektrograph for observing the absorption spectrum, and by employing both a Berek- and a Brace-Köhler compensator for polarization measurements. Autopsy material was obtained from the ribs of 35 children and adults at the age of 0 to 22 years. Refractivity was measured in stained and unstained paraffin sections, whereas dichroism and metachromatic index (MI) of the fibers were determined in stained specimens. All three parameters showed characteristic, quantitative age-dependent variations indicating that the highest degree of molecular and structural adjustment and alignment of the fibers is already being reached at the age of 8 years. The continuously higher refractivity of the fibers with increasing age and bone maturity may be explained by a progressive loss of water by the fibers.