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Quantitative histology of cartilage vascular canals in the human rib. Findings in normal neonates and children and in achondrogenesis II-hypochondrogenesis.

Knowledge of the structure of cartilage vascular canals is important for a more thorough understanding of the development of cartilage and the growth plate in the human neonate and growing child. We have studied the costochondral junction of 6 normal neonates and 12 normal children (age 4 months-16 years) and utilised quantitative histomorphometry to define the percentage tissue area occupied by canals and the number of canals/mm2. Both percentage canal area and the number of canals/mm2 were significantly greater in newborn vs. older children (percentage area: 0.42 +/- 0.15 (mean +/- S.E.M.) vs. 0.08 +/- 0.04, P = 0.003; number/mm2: 0.2 +/- 0.09 vs. 0.04 +/- 0.02, P = 0.02). Eight newborn patients with achondrogenesis II-hypochondrogenesis were also studied. Both percentage canal area and number were significantly elevated above normal (percentage area: 5.22 +/- 1.01, P less than 0.001; number/mm2: 1.45 +/- 0.26, P less than 0.001). Results presented here demonstrate that: (i) quantitative differences in vascular canal area and numbers occur during development; (ii) 10-fold increases in vascular canal area and number are present in achondrogenesis II-hypochondrogenesis. Data from normal subjects will provide normative values against which vascular abnormalities in other skeletal dysplasias can be compared.