Myosatellite cells associated with different muscle fibre types in the Atlantic hagfish (Myxine glutinosa, L.).

The incidence of myosatellite cells associated with "white" and "red" muscle fibres of the parietal muscle and "red" fibres of the craniovelar muscle was estimated by quantitative electron microscopy in the Atlantic hagfish (Myxine glutinosa, L.). Myosatellite cell nuclei constitute 3, 11 and 23% of the total number of nuclei inside the basal lamina of the three types of muscle fibres, respectively.

On T-tubule openings at the sarcolemma of white fast-twitch muscle fibres in fish and frog.

In "white" muscle fibres of a teleost fish T-tubule openings may occur regularly at all Z-disc levels between adjacent peripheral myofibrils, the T-tubule openings thus occurring at a density of ca. 0.9 micrometer-2.

Histochemical definition of muscle fibre types in the trunk musculature of a teleost fish (cod, Gadus morhua, L.).

Cryostat sections incubated for myofibrillar ATPase, SDH, LDH, and alpha-GPDH as well as p-phenylene-diamine stained semithin sections were used to define muscle fibre types in the trunk musculature of the cod (Gadus morhua, L.). Three zones (superficial, intermediate, deep) containing different muscle fibre types are present within both epaxial and hypaxial parts of each myomere subjacent to the lateral line.

Tubules invaginating from the sarcolemma in the subneural region of muscle fibers.

Sarcoplasmic tubules invaginating from the sarcolemma of the subneural region of muscle fibers are described in Atlantic hagfish and rat. In rat, the tubules invaginate from the bottoms of the secondary synaptic clefts. The density of tubule openings may be higher than the density of T-tubule openings elsewhere along muscle fibers.