The postnatal development of the inferior oblique muscle of the cat

Abstract

Transversal sections of the inferior oblique muscle from kittens of various ages and from adult cats were stained for myofibrillar ATP-ase at Ph 9.4 and 4.35, succinic dehydrogenase (SDH) and fat. The same muscles had previously been submitted to studies of contractional and fatigue properties. With ATPase the fibers could be differentiated into types I, II and II C. The percentages of each fiber type remained approximately the same from birth onwards. In the inner, global layer of the muscle, type I fibers showed a linear increase in size, but types II and IIC fibers an accelerated growth after age 20 weeks. In the outer, orbital layer, where no type I fibers were seen, type II and II C fibers showed the same growth pattern as in the global layer. The fiber content of SHD and fat was low at birth but increased after two weeks of age. Type I fibers were poor and type II C fibers rich in SDH and fat. Type II fibers showed varying amounts of these substances. Provided that type I fibers are slow, type II fast and type II C intermediate in speed of contraction, like in other muscles, the findings on fiber growth and SDH content seem to support the idea that slow, fatigue resistant components in eye muscles reach maturity earlier than fast components.

Skeletal Muscle

“…The histochemical and electron microscopic results described are basically in harmony with those of other studies (bank vole, KACZMARSKI 1970b; rabbit, CHENG-MINODA et al 1968;HOPKINS 1975;DAVIDOWITZ et al 1980a;rat, YEL-LIN 1969a;HANSON and LENNERSTRAND 1977;NAG and CHENG 1982;cat, PEA-CHEY et al 1974;HANSON et al 1980;LENNERSTRAND 1980;rhesus monkey, CHENG andBREININ 1965, 1966;MAYR et al 1966;MILLER 1967MILLER , 1971). There is, however, disagreement with respect to the presence or absence of M lines in slow fibres of mammalian extraocular muscles.…”

“…The twitch fibre types vary in diameter and mitochondrial content, all are type II fibres (rat, MAYR 1971;NAG and CHENG 1982;sheep, HARKER 1972a;rhesus monkey, MILLER 1967rhesus monkey, MILLER , 1971cat, ASMUSSEN et al 1971;HANSON and LENNERSTRAND 1977;HANSON et al 1980;rabbit, ASMUSSEN et al 1971). Two fibre types are multiply innervated and are slow fibres, they occupy Mammals 219 5%-10% of the cross-sectional area (see Chap.…”

Fibre types in extraocular muscles: a new myosin isoform in the fast fibres

“…1974a), some of which consist of multiply innervated non-twitch fibres that respond to repetitive stimulation or aceylcholine treatment with long-lasting contractures, like the slow-tonic fibres of amphibian muscle (Hess & Pilar, 1963). The histochemical profile of EO muscles is consistent with the results of physiological studies: type 2 fibres showing alkalistable and acid-labile myosin ATPase reaction similar to that of fast skeletal muscle fibres represent the major component fibre population, while type 1 fibres showing alkali-labile and acid-stable myosin ATPase reaction like slow skeletal muscle fibres represent a minor fibre population (Asmussen et al, 1971;Hanson et al, 1980;Vita et al, 1980). However, histochemical and ultrastructural studies have revealed a wide heterogeneity of fibre types in EO muscles and atypical pattern of reactivity in many of these fibres (Yellin, 1969;Mayr, 1971;Asmussen et al, 1971;Peachey et al, 1974;Alvarado & van Horn, 1975;Vita et al, 1980;Gueritaud et al, 1984).…”

Classification and Development of Myofiber Types in the Superior Oblique Extraocular Muscle of Chicken

“…It is currently not known how such precise control and adjustment is achieved. Maturation of EOM fibers occurs during a critical period of development and eye opening in mammals (Hanson et al, 1980), which correlates with major changes in motoneuron activity and maturation of visuomotor systems (Cheng et al, 2003; Spencer and Porter, 2006). Such descending functional or trophic neuromuscular influences appear critical for the remodeling and final composition of muscle fiber types that generate appropriate forces (Maier et al, 1972; Sohal and Sickles, 1986; Gundersen, 1998; Pette and Staron, 2000, 2001; Spencer and Porter, 2006).…”

“…Myofibers have been grouped into different categories based on anatomical location (orbital, global layer, or intermediate marginal), color (red, intermediate, or white/pale) that correlates with aerobic (red) and anaerobic (white) metabolism, and innervation patterns (singly innervated or multiply innervated). This approach commonly distinguishes at least six EOM fiber types in mammalian species (Hanson et al, 1980; Nag and Cheng, 1982; Pachter, 1982; Spencer and Porter, 1988; Porter et al, 1995). The orbital layer typically contains one (Spencer and Porter, 1981; Spencer and Porter, 2006) or more singly innervated muscle fiber types (Harker, 1972; Pachter and Colbjornsen, 1983; Pachter, 1983; Kjellgren et al, 2003) and one unusual type of multiply innervated muscle fibers.…”