Posthatch development of the axial musculature of the common dentex Dentex dentex, L (Teleostei)
O. López Albors1, M. Arizcun2, E. Abellán2, A. Blanco3, M.D. Ayala1, L.M. Pastor4 and R. Latorre1
1Department of Anatomy and Comparative Pathology, University of Murcia, Murcia, Spain, 2Centro Oceanografico de Murcia, Spanish Oceanographic Institute, Puerto de Mazarrón, Spain, 3Department of Anatomy and Comparative Pathology, University of Cordoba, Campus de Rabanales, Cordoba, Spain, and 4Department of Cell Biology and Histology, University of Murcia, Murcia, Spain.
Offprint requests to: O. López Albors, Department of Anatomy and Comparative Pathology, University of Murcia, 30100 Murcia, Spain. e-mail: firstname.lastname@example.org
Summary. The common dentex is a promising candidate for Mediterranean aquaculture. The present work is aimed at describing the development of the axial musculature from hatching to postlarval life. Transmission electron microscopy, histochemical (NADH-TR and mATPase) and immunohistochemical techniques (S-58 and TUNEL) have been used. At hatching superficial red and deep white muscles can be distinguished. Presumptive dermomyotome (external) cells are initially located over the superficial red muscle but shortly (2 days) tend to concentrate towards the epaxial and hipaxial limits of the myotome. Then, these cells enter the myotome and spread around and within the white muscle thus being apparently responsible for the stratified hyperplasia of the myotome. Mosaic hyperplasia is activated during the second half of the larval period and initially relies on differentiation of a population of atypical premyoblastic cells (APC). APC are mononuclear cells with euchromatic nuclei, cytoplasms full of thin longitudinally projected tubules, occasional mitochondria and scattered ribosomes. By the end of the larval period these cells tend to disappear, partly due to apoptosis, but postlarval mosaic hyperplasia continues by differentiation of presumptive myosatellite cells. APC are an unexpected and singular finding of this study which deserves more research, so as to further characterize their ancestry, developmental programme and fate. In addition to the white and superficial red muscle fibres, intermediate (pink) and tonic fibres appear during larval metamorphosis. Later, during the early postlarval life, a new type of slow twitch red muscle fibre is differentiated (red adult type). Histol Histopathol 25, 1557-1571 (2010)
Key words: Fish muscle, Dentex, Development, Myogenesis, Apoptosis