Inhibition of muscle growth in foetal sheep

Abstract

SummaryEighteen foetal sheep were used to study the relationship between suboptimal growth and linear size of skeletal units, dry weights of representative muscles and muscle histology. Foetuses with suboptimal growth caused by inadequate maternal nutrition and competition with other foetuses showed a decrease in skeletomuscular growth although allometric growth was not affected. A slight correlation (r =0·14, P < 0·005) existed between dry weight of the longissimus dorsi and mean minimum myofibre diameter. On morphological evidence, myofibre hyperplasia was thought to be complete by approximately 80 days gestation in all foetuses. Increases in the number of myofibres crossing mid-length transverse sections of the sartorius occurred after this time but were thought to be due to intrafascicularly terminating myofibres growing in length. Suboptimal muscle growth of foetuses in the latter third of gestation was thought to be associated with an inhibition of growth in length of intrafascicularly terminating myofibres.