I. Normal Chemical Composition and Growth

Introduction  This publication relates to the chemical dynamics of skeletal growth in the normal immature male rat. Data presented are introductory to a combined chemical, radiological, and histological interpretation of skeletal growth in this animal from birth through 75 days of age.*During this period of life in the rat, individual skeletal parts as well as the skeleton as a whole undergo continuous and often disproportionate changes in growth and development.† The following studies were undertaken to correlate chemical growth and turnover of the entire skeleton with serial changes in the chemical anatomy and linear growth of long bones.

Methods and Materials  Male Wistarwere used throughout this study. Litters were arranged at birth to contain approximately 8 to 18male animals. All animals were weaned at 21 days of age to a standard diet (Diet 1),‡ which contained 0.76% calcium and 0.44% phosphorus by wet weight, with a calcium-phosphorus ratio of 1.7.onstant source of