This paper describes the histomophological character of the skeletal muscle of El-Salam strain from HH12 (Day 2, D2) to HH27 (D5) during incubation period by using the light microscope and scanning electron microscope. Twenty eight embryos with age range from stage HH12 (D2) to HH27 (D5). During HH12 stage, the first three newly formed somites (SI to SIII) were composed of an outer columnar epithelial layer and a mesenchymal core in the center. SI was slightly elongated, larger than SII and SIII, but SIII was smaller than SII and became spherical. The differentiated somites have two main components, dermomyotome and sclerotome, separated by myocoele. At HH20 (D3) stage, somites have three components; dermomyotome, sclerotome and myotome. At HH24 (D4) stage, the epaxial myotome and the dorsomedial lip of the dermomyotome became larger than hypaxial myotome and the ventrolateral lip of the dermomyotome due to hypaxial myotomal cells migrated faster than the epaxial cells. By HH 27 (D5) stage, the dermomyotome disappeared and it became difficult to distinguish cells of dermatome, myotome and sclerotome. Our results should provide a foundation for understanding the histomorphological changes of skeletal muscle during development and growth in El-Salam chicken which subsequently can help researchers to improve meat production in these chickens.
chicken; somite; dermatome; dermomyotome; myotome; sclerotome