Types of muscle fibers in the extraocular muscles of birds (original) (raw)
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Descriptive and functional morphometry of skeletal muscle fibres in wild birds
Canadian Journal of Zoology, 1999
The fibre types of four forelimb and two hind-limb muscles involved in locomotion were morphometrically analyzed in three species of wild birds: the mallard (Anas platyrhynchos), common coot (Fulica atra), and yellowlegged gull (Larus cachinnans). Fibre cross-sectional area and perimeter, maximal diffusion distance, and number of capillaries per fibre were measured and the functional implications and physiological demands of the muscles of each species were inferred. In general, all morphometric values were lower in oxidative fibres than in anaerobic fibres, indicating that the supply of oxygen and metabolites available to aerobically working muscles is enhanced. The lower level of activity required during gliding as opposed to flapping flight, and the need to maintain the wings in an outstretched position, presumably by means of isometric contractions, may explain the greater size of the oxidative fibres of the pectoralis and scapulotriceps muscles of the gull. In contrast, the high oxidative demand imposed on mallards and coots by sustained flapping flight is met by small oxidative fibres, possibly at the expense of a reduction in the ability of each fibre to generate force. Anaerobic fibres of the gastrocnemius muscle had greater cross-sectional areas in the mallard and coot than in the gull. This is interpreted as an adaptive response to force generation during burst locomotion, which is usually performed by both mallards and coots, in sharp contrast to the buoyant swimming and postural activities undertaken by gull's legs. The fast oxidative fibres of the gastrocnemius muscle were, in general, larger than those of the iliotibialis muscle in the three species, which matches the different mechanical and functional roles of these muscles during swimming. Résumé : Les types de fibres dans les muscles responsables de la locomotion, quatre muscles des membres antérieurs et deux muscles des membres postérieurs, ont fait l'objet d'une analyse morphométrique chez trois espèces d'oiseaux en nature, le Canard colvert (Anas platyrhynchos), la Foulque macroule (Fulica atra) et le Goéland leucophée (Larus cachinnans). La surface des fibres en coupe transversale, leur périmètre, les distances maximales de diffusion et le nombre de capillaires par fibre ont été mesurés et ces mesures ont permis de déduire les conditions de fonctionnement, de même que les besoins physiologiques des muscles de chaque espèce. En général, toutes les mesures morphométriques se sont avérées plus basses dans les fibres oxydatives que dans les fibres anaérobies, ce qui indique que la quantité d'oxygène et de métabolites fournie aux muscles à fonctionnement aérobie est supérieure. L'activité moins importante reliée au vol plané par opposition au vol avec battements d'ailes et la nécessité de maintenir les ailes étendues, probablement par l'intermédiaire de contractions isométriques, explique probablement la taille plus grande des fibres oxydatives du pectoralis et des scapulotriceps chez le goéland. En revanche, le besoin important d'oxygène pour assurer le battement des ailes chez le colvert et la foulque est fourni par les fibres oxydatives de petite taille, ce qui se traduit probablement par une diminution de la force que peut générer chaque fibre. Chez le Canard colvert et chez la foulque, les fibres anaérobies du gastrocnémien ont une surface plus grande en coupe transversale que celles du goéland. Il semble qu'il s'agisse là d'une adaptation au déploiement d'une force au cours d'un déplacement subit, une tactique utilisée couramment par le colvert et la foulque, tactique totalement différente de la nage par flottaison et des activités reliées à la posture associées aux pattes du goéland. Les fibres oxydatives rapides du gastrocnémien sont en général plus grosses que celles du muscle iliotibialis chez les trois espèces, ce qui correspond aux rôles mécanique et fonctionnel de ces muscles au cours de la nage.
Quantitative ultrastructure of histochemically identified avian skeletal muscle fiber types
The anatomical record, 1987
A cryostat retrieval method and combined adenosine triphosphatase (ATPase) and acetylcholinesterase (AChase) method were used to study the ultrastructure and innervation of histochemically identified skeletal muscle fibers in different pigeon muscles. The Z-line structure and volume percentage sarcotubular system were analyzed from different muscles selected for their composition by fiber type. Histochemically, three main fiber types were investigated: slow tonic fibers with a moderate ATPase activity after preincubation at acid or alkaline pH; fast-twitch fibers that had high activity after alkaline treatment and low activity after acid preincubation; and a type considered to be slow-twitch that had low activity after alkaline, and high after acid preincubation. Both the slow tonic and slow-twitch fibers had multiple, en grappe innervation, while the fast-twitch fibers had robust, single end plates. The Z-line of the fast-twitch and slow-twitch fibers had a regular square lattice pattern, in contrast to the granular, nonlattice structure of the slow tonic Z-line. The volume percentage sarcotubular system of the slow-twitch fibers was intermediate between and significantly different from that of the fasttwitch and slow tonic fibers. These correlative analyses suggest that the avian muscles contain not only the fast-twitch and slow tonic fibers previously known, but also a slow-twitch fiber that appears to be intermediate between the tonic and the mammalian slow-twitch fiber type. Based on the abundance of the sarcotubular system, this fiber type appears to be fast-contracting and-relaxing, in spite of being multiply innervated. The characterization of skeletal muscle fiber types is important for clinical, functional, and developmental studies because there may be fiber type specificity of the muscles' reactions to various experimental, ontogenetic, and pathologic changes. It is clear that a variety of
Innervation Distribution Pattern, Nerve Ending Structure, and Fiber Types in Pigeon Skeletal-Muscle
Anatomical Record, 1993
Six muscles of the mallard duck (Anas platyrhynchos), the common coot (Fulica atra) and the yellow-legged gull (Larus cachinnans) were analysed morphometrically, with special emphasis on their functional implications and physiological needs. Oxidative fibres always had significantly smaller size than anaerobic fibres, although no differences in the number of capillaries per fibre were found. This resulted in greater capillary counts per unit of fibre area and perimeter in oxidative than anaerobic fibres, which indicates that the greater demand for oxygen supply may be achieved by decreasing the size of the muscle fibre rather than by increasing the number of associated capillaries. Fast oxidative fibres of the pectoralis and the triceps of the gull had greater sizes than the fast oxidative fibres of the mallard and the coot, which correlates with the difference in energetic demands between flapping and gliding flight. Greater fibre cross-sectional areas and perimeters seem suited to afford the long-lasting activity with low metabolic demands required during gliding. By contrast, mallards and coots attain a high oxidative metabolism, during sustained flapping flight, by reducing fibre size at the expense of a diminished ability for force generation. Between-species comparisons of the hindlimb muscles only yielded differences for the anaerobic fibres of the gastrocnemius, as an important adaptive response to force generation during burst locomotion. The need to manage sustained swimming abilities effectively may result in similar FOG fibre morphometry of the hindlimb muscles studied, indicating that a compromise between the oxygen flux to the muscle cell and the development of power is highly optimised in oxidative fibres of the bird species studied.
Acta Biologica Hungarica
The aim of the study was to describe the morphology and the development of the extraocular muscles (EOMs) in the pre-hatchling and post-hatchling African black ostrich. The study involved 50 birds aged between 28 days and 3 years. The EOMs were analyzed morphologically with respect to the location and length of the straight and oblique muscles and the third eyelid muscles, the length and breadth of their tendons as well as the distance and shape of the muscle tendon insertions at the corneal limbus. A histological and histometric analysis were also carried out. The greatest increase in the length of the EOMs was noted in groups III-V. A marked increase in the length of the tendons of the dorsal straight muscle was found in groups II and III, in the tendons of the nasal straight muscle in groups IV and V, in the tendons of the dorsal oblique muscle in groups III to V and in the tendons of the ventral oblique muscle in groups IV and V. There was a significant increase in the breadth of the dorsal straight and ventral oblique muscle tendons in groups IV and V and the tendons of the pyramidal muscle in groups III and V. The distance of the distal insertion of the tendon at the corneal limbus increased steadily with age in all the examined groups. The number of fascicles and muscle fibres, their diameter and length in all the studied EOMs were different in the different groups.
Ultrastructure and contractures of the pigeon iris striated muscle
The Journal of physiology, 1971
1. The ultrastructure of adult pigeon iris muscle fibres has been described with emphasis on the distribution of the sarcoplasmic reticulum (SR). Contractures due to superfusion with solutions of different [K(+)] (3-150 mM) and acetylcholine (ACh) and their modification by alteration of external [Ca(2+)] and [Mg(2+)] were studied in isolated pigeon iris.2. The arrangement of the contractile myofilaments was like that of vertebrate skeletal fibres. The SR is well developed in the I-band and sparse at the A-band level. Tubular elements (T-system) which form triads with the SR were seen at all levels of the sarcomere though usually adjacent to the A-I junction.3. K(+) contractures developed monotonically to a steady level which was maintained for the duration of the high [K(+)] superfusion. The response to a standard [K(+)] stepwise change was not altered by conditioning the preparation with various [K(+)].4. Decreasing external [Ca(2+)] from 20 mM to Ca(2+)-free (i.e. no Ca(2+) added)...
Comparative Micromorphological Study on the Pectoralis Muscle in the Flying and non-Flying Birds
2017
The pectoralis major muscle of twenty adult female fowl and pigeon were examined using histological, histochemical and transmission electron microscope "TEM" methods. In addition to morphometric, histomorphometric, and enzyme activity determination methods were also performed. The histological examination showed that the pectoralis major muscle fibers of fowl run in different directions with few blood capillaries and more distinct cross striations. The opposite picture was found in pigeon. Histochemical stains showed more pronounced glycogen granules and myoglobin in pigeon muscle. The calcium granules were unequally distributed in both fowl and pigeon muscle. Ultrastructurally, the muscle fibers of this muscle in the fowl had different thickness and wide sarcomeres with thin Z-lines. The reverse structure was present in case of pigeon. Large numerous electronlucent lipid droplets were observed in pigeon muscle and not observed in fowl. Morphometric parameters and statisti...
Regeneration of Pigeon Fast and Slow Muscle Fiber Types After Partial Excision and Mincing
Journal of Cell Biology, 1974
The pigeon's metapatagialis muscles, containing fast fibers in two slips and slow fibers in another slip, were excised for a third of their length, minced, and replaced into their previous sites. After regeneration, the pattern of fiber types and their ATPase and oxidative enzymes were examined histochemically. Ultrastructural examination was carried out on the fast fibers. After 4-17 wk the muscles had regenerated into patterns histochemically similar to the controls only within the slip containing fast fibers. The slow slip was much less regenerated, and had a histochemically embryonic composition. Fiber types were characterized and their cross-sectional areas measured, and the degree of atrophy was greatest in the large fast fibers and the slow fibers. Ultrastructural studies revealed a number of alterations of the mitochondria, including dense and light areas in the matrix and an altered pattern of the cristae into parallel tubular or vesicular aggregations. Other changes included dilated sarcoplasmic reticulum, myofibril disorganization, and a compaction of filaments. The slow fibers were thought to be slower in their regeneration rates because of the pattern of multiple innervation's producing a more complex regenerative pattern .
Comparisons in the strucure of avian muscle spindes
The Journal of Comparative Neurology, 1971
A study of muscle spindles in several species of birds was made to determine if avian intrafusal (IF) fibers are separable into the nuclear bag and chain fiber types found in mammals, and whether prominent differences in spindle structure might exist among species. Van Gieson-stained serial sections of the sartorius, a flexor muscle, and the antigravity adductor profundus muscle were examined in the chicken, quail, pigeon and canary. Avian IF fibers did not exhibit the pronounced "bag" of nuclei characteristic of mammalian nuclear-bag fibers, although the non-striated region at mid-length was marked by a moderate excess of eccentric, vesicular nuclei. No consistent differentiation in pattern of nuclear aggregation or manner of fiber termination among fibers of a spindle was detected, nor was there unequivocal bimodality in cross-sectional areas. These characteristics in bird spindles, therefore, do not afford trustworthy criteria for separation of types of IF fibers. The number of spindles per unit volume was particularly high in the canary and lowest in the chicken muscles. Spindles in the chicken were larger and more complex than canary spindles in respect to numbers of fibers per spindle, spindle length, and cross-sectional area of intrafusal fibers at the equator. Values for the quail and pigeon occupied an intermediate position. Relation of the differences in spindle structure to the size of the bird and to other factors is discussed, and some contrasts between avian and mammalian spindles are pointed out.