LONGITUDINAL GROWTH OF SKELETAL-MUSCLE FIBERS IN LINES OF MICE SELECTED FOR HIGH AND LOW BODY-WEIGHT

  • 1 January 1976
    • journal article
    • research article
    • Vol. 40  (1) , 33-39
Abstract
The effect of selection for increased and decreased body wieght on the weight, mean fiber length, mean estimated resting fiber length, mean sarcomere length and mean sarcomere number per fiber of the biceps brachii muscle was studied in 10 wk old mice. The expected alterations in muscle weight were present and were due in part to changes in fiber length which was increased in the high line and decreased in the low line. The changes in fiber length were due to differences in sarcomere number per fiber which was increased in the high line and decreased in the low line. The mean sarcomere length of mice in the high and low lines did not differ significantly from control indicating that this parameter is unaffected by selection for altered body weight. Genetic factors probably influence longitudinal muscle fiber growth in 2 ways. Species differ in the length of their myofilaments whereas differences between individuals and lines within a species are due to the formation of additional sarcomeres.