Differentiation of muscle fiber types in the teleost Brachydanio rerio, the zebrafish

Abstract

The trunk musculature of adult zebrafishes contains three major fiber types: adult red, intermediate, and white; and two minor populations: red muscle rim and scattered intermediate fibers. In this paper, the post hatching development of these muscle fiber types was studied by means of immunohistochemistry, using anti-myosin sera. Just hatched larvae contain two muscle fiber populations: embryonic red and white, which give rise to the red muscle rim and the intermediate fibers respectively. Adult red fibers arise post hatching as a new separate population with distinct myosin properties. The differentiation of these fiber types occurs within the first four weeks after fertilization, when the adult pattern of peripheral axon bundles has become established. Differences in the muscle fiber type composition between the midbody and the tail myotomes become apparent in two month old fries. The number of scattered intermediate fibers increases from rostral to caudal, the opposite holds for the red muscle rim fibers. The red and intermediate area is triangular in the midbody; in the tail part it is stretched out along the lateral surface of the myotomes. These changes are considered as adaptations to improve the efficiency of the swimming performance.

Principles governing recruitment of motoneurons during swimming in zebrafish

“…At later developmental stages, zebrafish acquire red muscle fibers that appear two weeks after hatching 22 . The motoneurons innervating these fibers are located in the lateral aspect of the motor column 18,19 , but it is still unclear if these "red" motoneurons are a class of neurons that appear later during development (when red muscle fibers develop).…”

“…In zebrafish, motoneurons develop along the dorso-ventral axis with the early born, large primary motoneurons located dorsally and later born, small secondary motoneurons located ventrally [16][17][18][19] . At early developmental stages, zebrafish larvae swim in bursts and only embryonic muscle fibers are developed [20][21][22] . At later stages of development there is a slow increase in number of adult red (slow) muscle fibers that start to appear after two weeks post-hatching 22 .…”

“…At early developmental stages, zebrafish larvae swim in bursts and only embryonic muscle fibers are developed [20][21][22] . At later stages of development there is a slow increase in number of adult red (slow) muscle fibers that start to appear after two weeks post-hatching 22 . This is correlated with a change from burst swimming to the adult pattern of slow, steady swimming movements with continuously active red musculature [23][24][25] .…”

Increased neuromuscular activity causes axonal defects and muscular degeneration

“…Fast muscle fibers make up the bulk of somitic tissue and they constitute the medial surface along which primary motor axons migrate (Bernhardt et al, 1998;Van Raamsdonk et al, 1978;Van Raamsdonk et al, 1982;Westerfield et al, 1986). Slow muscle cells are derived from adaxial cells, which are initially located on the medial side of the myotome (Devoto et al, 1996), and have been shown to play important roles for motor axon guidance (Zeller and Granato, 1999;Zhang and Granato, 2000).…”

Hedgehog regulation of superficial slow muscle fibres inXenopusand the evolution of tetrapod trunk myogenesis

“…At a slightly later stage of development, lateral somitic cells give rise to the fast muscle that makes up the bulk of the myotome (Devoto et al, 1996). Subsequently, the myotome grows by the addition of further cell populations at its dorsal and ventral extremes, a situation reminiscent of the dorsomedial and ventrolateral dermomyotomal lips of amniotes (Barresi et al, 2001;van Raamsdonk et al, 1982;Veggetti et al, 1990).…”