Differentiation of the Jaw Adductor Muscle of the Rosy Barb, Barbus Conchonius (Teleostei, Cyprinidae, L.), During Development

Abstract

The differentiation of the jaw adductor muscle of the rosy barb, Barbus conchonius, has been studied during development to determine the relation between fiber type and early muscle activity. First, a morphological description and a functional analysis with electromyography has been made of the jaw adductor of the adult fish. Based on this analysis and on histochemical characteristics, the jaw adductor muscle can be divided into two parts: an aerobic part, which shows contractile activity during respiration, and an anaerobic part, which is silent during respiration. Secondly, the jaw adductor muscle of embryonic and larval specimens of the barb was investigated (immuno)histochemically. From the fourth day after fertilization onwards, deeply located future-red fibers and more superficial future-white fibers can be distinguished histochemically. From the juvenile stage onwards (30 days after fertilization), the histochemical pattern of the jaw adductor is identical to that of the adult. Results are discussed in relation to the start of respiratory and feeding behaviour during development.

Functional Properties of the Feeding Musculature

“…In both taxa the adductor had two parts, one with small, low-ATPase, oxidative fibers active during respiration and the other with larger, less oxidative fibers active only during feeding. Barends et al (1983) also reviewed earlier work on teleost jaw adductors, mostly showing a similar division between aerobic and anaerobic portions. It should be noted that all of the above authors distinguished multiple fiber types, usually four to five, making the reduction to two groups an oversimplification.…”

“…The first group had only fast, lowmitochondria fibers, while the second group had high-mitochondria fibers of variable ATPase activity. Barends (1979) and Barends et al (1983) compared various parts of the m. adductor mandibulae in the perch and in the rosy barb, Barbus conchonius. In both taxa the adductor had two parts, one with small, low-ATPase, oxidative fibers active during respiration and the other with larger, less oxidative fibers active only during feeding.…”