Growth related increase in rat intervertebral disc size: a quantitative radiographic and histologic comparison

Methods were developed for measuring the width of lumbar intervertebral discs in Sprague-Dawley rats. Rates of growth of the L4-5 and L5-6 discs in a rostral-caudal direction in an approximately midsagittal plane were reported from analysis of radiographic and histologic data. The radiographic data correlated with histologic data (p less than 0.001). It was concluded that the L4-5 and L5-6 intervertebral discs continue to increase in size throughout the first 18 months of life of the rat, well past the age of rapid gain in body weight.