Abstract
The role of variation in end-organ cartilage response to somatomedin (SM) as a significant determinant of growth velocity has been investigated.The response of costal cartilage of foetal and post-natal rabbits to SM has been assessed by simultaneously measuring 35S and 3H-thymidine uptake in vitro. Cartilage from rabbits of known growth rate at 23 and 30 days after conception (gestation 33 days), and at 1, 7, 17, 28, 39, 64, 90 and more than 200 days after birth, was studied. An excellent correlation between thymidine uptake and the growth velocity of the costal cartilage was shown. The uptake of 35S was also closely related to growth velocity and the 3H/35S ratio declined as growth rate slowed.Serum SM of each age group was measured by the porcine cartilage technique of Van den Brande. The post-natal serum SM increased progressively with age to an adult plateau.This study suggests that the growth velocity of costal cartilage is determined by the combined effects of end-organ response and serum SM stimulus.
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