Development of the Myotomal Musculature in the Red Sea Bream

Abstract

The developmental process of the myotomal musculature in the red sea bream was investigated histochemically from newly hatched larvae to juveniles, and histochemical characters of the fiber types were confirmed in young specimens. Three main fiber types, so-called red, pink and white, were recognized on the basis of differences in fiber size and the staining for SDH, NADHD, PhR and lipid. In addition to these three types, there were very small diameter fibers between the red and pink fiber zones, showing very weak or negative staining for SDH, NADHD, PhR and lipid. Newly hatched larvae were provided with a single layer of presumptive myoblasts of the superficial fibers surrounding the inner white fibrs. The myofibrils of superficial cells became evident by 2.9mm TL, and metabolic features referable to the red fiber type appeared in these cells prior to the first-feeding stage. At about 7mm TL, the pink fibers started to differentiate and the stratification of muscle fibers occurred in the red fiber zone, foreshadowing the definitive adult arrangement. The developmental process of the myotomal musculature seemed to be correlated with the swimming behavior of these larvae and junveiles.