Embryonic muscle development in rainbow trout (Oncorhynchus mykiss): A scanning electron microscopy and immunohistological study

Abstract

Embryonic muscle development was studied in rainbow trout (Oncorhynchus mykiss) at low and high temperature using scanning electron microscopy (SEM) and immunohistology. Somite development was described starting at stage 16 (Vernier JM. 1969. Ann Embryol Morphogen 4:495–520) for both temperatures, with special interest in their shape and size. Muscle differentiation, associated with somite growth, is characterized by a larger increase in height compared to width and by acquisition of a chevron shape. Thin structures such as striation, sarcomeres, and myofibrils within muscle cells and myotubes were observed starting at the eyed stage (stage 24). Immunohistological analyses showed appearance of embryonic fast myosin at stage 20 in the deep part of the somite. The area where myosin was expressed extended in the somite throughout embryonic development and the presence of myosin was observed in the entire somite at hatching (stage 30). Slow myosin was expressed in a monolayer of superficial cells at the eyed stage and during the entire embryonic development. Then it was expressed in a few layers of cells located in the red muscle area. These results suggest that muscle differentiation, characterized by myosin expression, is engaged at stage 20. Myogenesis starts in the deep part of the somite, near the notochord and progresses laterally to cover the complete somite at hatching when the somite is composed of muscle fibres exhibiting a high degree of maturity. No significant difference was observed in terms of muscular development between low‐ and high‐temperature conditions. J. Exp. Zool. 286:379–389, 2000. © 2000 Wiley‐Liss, Inc.

Variable impacts of L-arginine or L-NAME during early life on molecular and cellular markers of muscle growth mechanisms in rainbow trout

“…The rate of somitogenesis observed here (5.7 somites formed/day at 8 °C, i.e. 0.7 somite formed/degree-day) is consistent with previous observations in the same species (Bobe et al, 2000). Other data with rainbow trout have indicated that the initial differentiation of fast (white) muscle takes place in proximity to axial structures and that fmhc transcript is detected from 25 somites onwards (Rescan et al, 2001).…”

Cloning and characterization of microRNAs from rainbow trout (Oncorhynchus mykiss): Their expression during early embryonic development

“…Embryonic genome activation occurs at mid-blastula stage in fish. According to Bobe and coworkers (2000), mid-blastula stage of rainbow trout embryos (cultured at ~12°C) occurs 2-dpf [35,36]. So, maternal mRNA degradation and EGA in rainbow trout could occur around 2-dpf.…”

Mixed Mesodermal and Mesenchymal Origin of Myotomal Muscles in Pike (Esox lucius: Teleostei)

“…Comparative studies on myogenesis showed that in vertebrates the process does not follow a common developmental pathway, and the ways leading to formation of multinucleate muscle fibres in early embryogenesis are different in fishes, amphibians, birds and mammals (reviewed by Kiełbówna and Daczewska, 2004). In fishes, at early stages of myogenesis, primary myoblasts (of mesodermal origin) differentiate into multinucleate muscle lamellae in Siberian sturgeon ( Acipenser baeri ) and starry sturgeon ( Acipenser stellatus ) (Flood and Gulyaev, 1987; Daczewska and Saczko, 2005) or form multinucleate myotubes in European grayling ( Thymallus thymallus ), rainbow trout ( Oncorhynchus mykiss ), European pearlfish ( Rutilus frisii meidingeri ) and Atlantic salmon ( Salmo salar ) (Merkel, 1995; Stoiber et al., 1998; Johnston, 1999; Bobe et al., 2000). In amphibians myotomal cells were observed to differentiate into mononucleate, morphologically and functionally mature muscle cells in African clawed frog ( Xenopus laevis ), and African dwarf frog ( Hymenochirus boettgeri ) (Daczewska, 2001; Kiełbówna and Daczewska, 2005), or else multinucleate myotubes form directly in European spadefoot ( Pelobates fuscus ), pool frog ( Rana laessonae ), and smooth newt ( Triturus vulgaris ) (Daczewska and Pałucka, 1999; Daczewska and Kiełbówna, 2000).…”