AnSci336 - Lecture 11

Explicitly distinguishe muscle regeneration from normal postnatal growth, since satellite cells can contribute to both processes through different mechanisms.

Normal postnatal muscle growth occurs primarily through hypertrophy of existing muscle fibers. Satellite cells can fuse with existing fibers to provide additional myonuclei and support growth. In contrast, muscle regeneration occurs following injury, when activated satellite cells proliferate and differentiate to repair damaged fibers or form new muscle fibers

Emphasizes how determinate versus indeterminate growth relates to postnatal muscle fiber hyperplasia.

Determinate growers, such as most mammals and birds, reach a relatively defined mature size, and muscle fiber hyperplasia occurs primarily before birth or hatching. Indeterminate growers, such as many fish, can continue growing after maturity and may generate additional muscle fibers through postnatal hyperplasia

Separate radial growth (increased diameter) from longitudinal growth (increased length), reinforcing the mechanisms discussed in Slides 26–29.

• Radial growth: Muscle fiber diameter increases through the accumulation of myofibrillar proteins and additional myofibrils, potentially involving longitudinal splitting of existing myofibrils

• Longitudinal growth: Muscle fiber length increases primarily through the addition of sarcomeres in series, particularly at the ends of myofibrils, in response to skeletal growth and mechanical stretch

BLANK SPACE

BLANK SPACE