Table 2 Stages of the fetal and postnatal development of porcine skeletal muscle

1

From conception to 25 d of gestation

Embryonic myogenesis from a common mesenchymal precursor

2

From 25 to 50 d of gestation

Formation of primary muscle fibers (rapid fusion of primary myoblasts)

3

From 50 to 90 d of gestation

Formation of secondary muscle fibers (formed on the surface of primary fibers)

4

From 90 to 95 d of gestation

Establishment of muscle fiber numbers

5

d 114 of gestation

Total numbers of muscle fibers are fixed at birth

6

After birth

Growth of skeletal muscle by increasing the size of its fibers (hypertrophy)^a; and maturation of skeletal muscle