A longitudinal genetic study of tail tendon fibre break time.

Tail tendon fibre break time (TTFBT), an indicator of collagen cross-linkage, was measured longitudinally in C57BL/6, DBA/2 and B6D2F1 mice, and F2 and backcross genotypes. TTFBT was assessed at 50, 150, 300 and 450 days of age. The distribution of means of these six genotypes suggests substantial genetic influence on this phenotype. Broad sense heritability, as assessed in a classical biometrical analysis, was negligible at 50 and 150 days, but accounted for between 25 and 43% of the variance at 300 to 450 days. The stability and reliability of TTFBT were also examined. Reliability was extremely high for each occasion; stability increased from moderate to substantial levels with increasing age, and may be influenced by heterozygosity.