scholarly journals Histology of Muscle Development in Pigs, Epigenetics from Myotubes to Tapered Fibres

2021 ◽  
Vol 9 (6) ◽  
Author(s):  
Howard J. Swatland
Keyword(s):  
Connective Tissue ◽  
Muscle Fibre ◽  
Radial Growth ◽  
Muscle Development ◽  
Transverse Section ◽  
Longitudinal Growth ◽  
Sartorius Muscle ◽  
Muscle Fibres ◽  
Peroneus Longus ◽  
Peripheral Position

Pre-natal muscle development in pigs starts with myotubes (axial nuclei in a tube of myofibrils) and secondary fibres (peripheral nuclei on an axial strand of myofibrils). By the time of birth, the nuclei of myotubes move to a peripheral position like secondary fibres. As pre-natal secondary fibres grow in length, the number of fibres in a transverse section may appear to increase. This stereology may also occur in post-natal muscles that have tapered fibres anchored in endomysial connective tissue around adjacent fibres and with one or both ends not reaching the end of their fasciculus. Up to 100 days gestation, Peroneus longus (no tapered fibres) had larger (P < 0.001) diameter secondary fibres than Longissimus thoracis (with tapered fibres). Up to 100 days gestation, no radial growth of secondary fibres was detected, but myotubes decreased in diameter (P < 0.001).  From a curve showing the relative numbers of myotubes and secondary fibres, it was deduced that approximately 80% of muscle fibres in pigs are derived from secondary fibres. In post-natal Sartorius muscle there was an increase (P < 0.005) in the apparent number of muscle fibres attributed to longitudinal growth of tapered fibres. Myotubes located centrally within their fasciculi had the same position as slow-contracting fibres with a high myoglobin content in adult muscle. Post-natal changes in muscle fibre histochemistry were achieved through transitional types, probably neurally regulated rather than by differential longitudinal growth of tapered endings. Secondary fibres are important – they give rise to both the majority of muscle fibres in adult pigs and affect subsurface optical pathways and pork colourimetry.

The effect of maternal undernutrition on muscle fibre type in the newborn lamb

2003 ◽  
Vol 2003 ◽  
pp. 60-60
Author(s):  
A.J. Fahey ◽  
J.M. Brameld ◽  
T. Parr ◽  
P.J. Buttery
Keyword(s):  
Muscle Fibre ◽  
Meat Quality ◽  
Fibre Type ◽  
Muscle Development ◽  
Nutrient Supply ◽  
Muscle Fibre Type ◽  
Growth Potential ◽  
Muscle Fibres ◽  
General Hypothesis ◽  
Maternal Undernutrition

Muscle fibre type can influence meat quality (Maltinet al1997). Muscle fibre formation occurs during gestation and in the sheep the total number of fibres in a muscle is essentially fixed at birth. (Ashmereet al1972). Postnatal growth of muscle is entirely due to elongation and widening of the existing muscle fibres. Therefore the gestational period is important in the long-term growth potential of the animal. By investigating changes in muscle fibre type, the aim of this study was to test the general hypothesis that the poor carcass quality sometimes seen in ruminant animals may be due to poor nutrition at strategic time points during the animal’s development. As agricultural practices continue to become more extensive, variation in the nutrient supply to the animal is becoming more common. Therefore it is important to understand the effect of any changes in nutrient supply to the mother, during gestation on the subsequent muscle development of the fetus and ultimately the effects on meat quality.

Embryonic growth and innervation of rat skeletal muscles. - III. Neural regulation of junctional and extra-junctional acetylcholine receptor clusters

1981 ◽  
Vol 293 (1065) ◽  
pp. 287-314 ◽  
Keyword(s):  
Muscle Fibre ◽  
Nerve Terminal ◽  
Time Course ◽  
Muscle Development ◽  
Muscle Cells ◽  
Diaphragm Muscle ◽  
Muscle Fibres ◽  
The Mean ◽  
Receptor Clusters ◽  
Ach Receptors

The number and distribution of acetylcholine (ACh) receptors on muscle cells was studied during development of normal, paralysed and aneural embryonic rat diaphragm muscles. (i) ACh receptors initially are dispersed over the surface of rat embryo myotubes. At day 15| of gestation junctional receptor clusters (‘J-clusters’) form in a well ordered band across the midline of the diaphragm muscle; these also form in denervated and paralysed muscles. At about day 18 of gestation additional ‘EJ-clusters’ develop to either side of the midpoint of treated muscles. (ii) If a nerve terminal is present, J-clusters increase in length with time. The time course of generation of new endplates calculated from frequency distributions of J-cluster lengths accurately predicts the muscle growth curve established from muscle fibre counts. (iii) The mean length of J-clusters in paralysed muscles was greater than in controls, due to small new-formed clusters failing to appear. In muscles allowed to recover from paralysis the mean length was less, due to a preponderance of small, new-formed clusters. These observations show that development of new endplates, which is thought to reflect the development of new muscle cells, is halted in paralysed muscles, and recovery from paralysis is associated with the generation of many new endplates. (iv) J-clusters appeared, but failed to grow, in aneural muscles. In muscles denervated during the later stages of gestation, analysis of the distribution of J-cluster lengths shows that new clusters failed to appear, and existing clusters showed little or no increase in length after the time of removal of the nerve. (v) EJ-clusters form by aggregation of dispersed receptors, and their mean length increases with time. They do not appear to be stable entities, and are removed within 2 d of recovery from paralysis. In paralysed muscles, with both J-clusters and EJclusters present, only J-clusters attract nerve sprouts or become innervated. (vi) A curve is derived showing development of the total number of synaptic terminals in a muscle. This number increases during days 13-18 of gestation, reaching a peak of about 170 % of the adult value during dl8 and d l9 of gestation. There are two episodes of terminal elimination, one during days 19-21 of gestation, and another about 2 weeks postnatally. During the first postnatal week the number of terminals remains constant at about 140% of the adult number, while the average number of inputs per fibre goes down and the number of muscle fibres increases. (vii) Innervation is essential for muscle development. Motoneurons cannot regulate the number of muscle fibres by requiring a simple one-to-one relation between nerve terminal and muscle fibre, and if their role is regulatory as well as supportive of muscle development then some more complex relationship between nerve terminals and developing myotubes must be postulated.

scholarly journals VIRTOPSY FOR STUDYING THE SUDDEN DEATH OF AN ADOLESCENT

2020 ◽  
Vol 6 (1) ◽  
pp. 41-45
Author(s):  
V. A. Klevno ◽  
Yu. V. Chumakova ◽  
O. A. Korotenko ◽  
D. I. Sandu ◽  
S. E. Dubrova
Keyword(s):  
Computed Tomography ◽  
Connective Tissue ◽  
Sudden Death ◽  
Ct Scan ◽  
Marfan Syndrome ◽  
Muscle Development ◽  
Dissecting Aneurysm ◽  
Ascending Aorta ◽  
Muscle Fibres ◽  
Body Type

The article discusses the application of pre-autopsy computed tomography (Virtopsy) for studying the sudden death of an adolescent with undiagnosed Marfan syndrome.Aim. To identify the capabilities of the pre-autopsy computed tomography (CT) in determining the cause of the sudden death of an adolescent, as well as the extent of injuries, if present.Material and methods. A CT scan was obtained at the Department of Diagnostic Radiology of a district hospital using a modern multifunctional CT scanner Siemens SOMATOM Perspective (64-slice configuration, slice width of 1.5 mm).Results. The forensic medical examination revealed the following information about the corpse: asthenic body type, a height of 178 cm, long extremities, thin and long spider-like fingers, pectus excavatum, little fat beneath the skin and poor muscle development; blood in the pericardium, rupture of the dissecting aneurysm of the ascending aorta. The histological examination of the aorta revealed its dramatic thinning, fragmentation of the elastic fibres along with the alteration of the elastic framework, fragmentation and poor development of muscle fibres in the media. A CT scan showed the rupture of the dissecting aneurysm of the ascending thoracic aorta with para-aortic haematoma and cardiac tamponade.Conclusion. The analysis of obtained data allowed us to diagnose a multisystemic disorder of connective tissue (Marfan syndrome) undiagnosed intra vitam. The sudden death was caused by the rupture of the dissecting aneurysm of the ascending aorta which is a complication of the congenital genetic pathology.Intravitam CT or MRI scans of children being at risk of the multisystemic disorder of connective tissue will help detect pathological changes in the aortic wall and perform cardiac surgery promptly which would significantly increase the length of life and improve its quality for such patients.

Distribution of acetylcholine receptors in the vicinity of nerve terminals on skeletal muscle of the frog

1972 ◽  
Vol 181 (1065) ◽  
pp. 431-440 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Connective Tissue ◽  
Neuromuscular Junction ◽  
Muscle Fibre ◽  
Nerve Terminal ◽  
Acetylcholine Receptors ◽  
Postsynaptic Membrane ◽  
Muscle Membrane ◽  
Muscle Fibres ◽  
Nerve Terminals

1. The acetylcholine (ACh) sensitivity of muscle fibres at the neuromuscular junction of the frog was investigated in preparations in which the nerve terminals could be clearly seen. 2. ACh released iontophoretically from a micropipette that was precisely positioned at various points along the muscle fibre in the vicinity of the synapse showed that the peak chemosensitivity (up to 1900 mV/nC) is confined to an area of postsynaptic membrane within a few micra of the nerve terminal; a tenfold decline in sensitivity was obtained when the ACh was released only 5 to 10 μm from the terminal’s edge. It is estimated that most of the response obtained when ACh is released within 40 μm from the terminal (the area covered in this study) is due to diffusion to the immediate postsynaptic area. The extrasynaptic chemosensitivity of the muscle membrane was too low to be measured with the present methods. 3. The accuracy with which micropipettes could be positioned in synaptic areas and the clarity of viewing nerve terminals were improved by bathing the tissue in collagenase, which reduced the amount of connective tissue. The distribution of chemosensitivity remained unchanged by such treatment. The ACh response was not detectably altered when nerve terminals were lifted off the muscle, exposing the subsynaptic muscle surface.

scholarly journals Number of conceptuses in utero affects porcine fetal muscle development

Reproduction ◽  
2004 ◽  
Vol 128 (4) ◽  
pp. 443-454 ◽  
Author(s):  
S C Town ◽  
C T Putman ◽  
N J Turchinsky ◽  
W T Dixon ◽  
G R Foxcroft
Keyword(s):  
Muscle Fibre ◽  
Muscle Development ◽  
Weight Ratio ◽  
In Utero ◽  
Muscle Fibres ◽  
Semitendinosus Muscle ◽  
Muscle Weight ◽  
Cross Sectional ◽  
Fetal Organ ◽  
Muscle Cross Sectional Area

Unmodified, third parity, control sows (CTR; n = 30) or sows subjected to unilateral oviduct ligation before breeding (LIG; n = 30), were slaughtered at either day 30 or day 90 of gestation and used to determine the effects of numbers of conceptuses in utero on prenatal, and particularly muscle fibre, development. Ovulation rate, number of conceptuses in utero, placental and fetal size, and (day 90 sows) fetal organ and semitendinosus muscle development were recorded. Tubal ligation reduced (P < 0.05) the number of viable embryos at day 30 and fetuses at day 90. Placental weight at day 30 and day 90, and fetal weight at day 90, were lower (P < 0.05) in CTR sows. All body organs except the brain were lighter, and the brain:liver weight ratio was higher in CTR fetuses (P < 0.05), indicative of brain sparing and intrauterine growth restriction in fetuses from CTR sows. Muscle weight, muscle cross-sectional area and the total number of secondary fibres were also lower (P < 0.05) in CTR fetuses. The number of primary fibres, the secondary:primary muscle fibre ratio, and the distribution of myosin heavy chain-Iβ, -IIa, fetal and embryonic isoforms did not differ between groups. Thus, even the relatively modest uterine crowding occurring naturally in CTR sows negatively affected placental and fetal development and the number of secondary muscle fibres. Consequences of more extreme crowding in utero on fetal and postnatal development, resulting from changing patterns of early embryonic survival, merit further investigation.

scholarly journals The surface membranes of muscle fibres

1937 ◽  
Vol 122 (827) ◽  
pp. 140-154 ◽  
Keyword(s):  
Action Potential ◽  
Muscle Fibre ◽  
Algal Cell ◽  
Surface Membrane ◽  
Sartorius Muscle ◽  
Muscle Fibres ◽  
Plant Vacuole ◽  
Injured Part ◽  
A Cell ◽  
Aqueous Layer

The electrical properties of muscle are best explained in terms of the state of polarization of the surface of the muscle fibre. The uninjured surface of an isolated frog sartorius muscle is equipotential. Localized injury causes the injured part to be electrically negative to the uninjured surface. This indicates that normally the outside of the surface is positive to the inside. The same condition appears to exist in nerve fibres. Stimulation of muscle or nerve causes an impulse to move along the fibre. This impulse is a phase of depolarization which passes longitudinally along the surface of the fibre. The action potential which is a consequence of the depolarization has been much studied, but little is yet known of the nature and properties of the surface membrane at which the depolarization occurs. A consideration of the results of studies on the electrical behaviour of large single plant cells promises to throw some light on this problem (Osterhout 1929, 1931, 1934, 1935). The protoplasm of a cell of Valonia or Nitella forms a layer about 10 μ thick surrounding an aqueous vacuole. This protoplasm consists probably of an outer and inner layer of non-aqueous material and an intermediate aqueous layer. The evidence for this derives from (1) the shape of the action potential curve, and (2) the fact that a circuit consisting of cell sap—protoplasmic layer—cell sap has a considerable e. m. f., which would not be so if the protoplasm were homogeneous. It is the purpose of this paper to apply the method of the second criterion to muscle fibre, and to study this “asymmetry” potential. It is difficult to apply the same criteria to a muscle as to a large single algal cell for the following reasons. (1) A muscle comprises many fibres and the response of the inner fibres to a solute in he external medium is governed by the time of diffusion of the solute into the muscle. (2) An algal cell and a muscle fibre are histologically dissimilar. (3) It is impossible to extract the semi-liquid contents of a muscle fibre in the way that sap can be taken from a large plant vacuole. And an aqueous solution cannot be prepared of the same inorganic salt composition as muscle fibre because the phosphate content is too high and causes precipitation of Ca and Mg.

An Unusual Type of Muscle-Fibre

1948 ◽  
Vol s3-89 (6) ◽  
pp. 139-141
Keyword(s):  
Connective Tissue ◽  
Muscle Fibre ◽  
Hollow Cylinder ◽  
Lumbricus Terrestris ◽  
Muscle Fibres ◽  
Single Nucleus ◽  
Unusual Type

The protractor muscles of the bristle-like chaetae of serpulids and sabellids consist of discrete fibres. Each fibre consists of a hollow cylinder of unstriped fibrils surrounded by a sheath of cytoplasm which is expanded into two or more frilled membranes extending along the fibre. The single nucleus lies in one of these membranes. The fibre is apparently ensheathed by a sarcolemma of fine connective tissue-fibres. Similar frilled membranes are present on the muscle-fibres in the walls of the ‘hearts’ of Lumbricus terrestris.

scholarly journals THE CAPILLARY PATTERN IN HUMAN MASSETER MUSCLE DURING AGEING

2013 ◽  
Vol 32 (3) ◽  
pp. 135 ◽  
Author(s):  
Erika Cvetko ◽  
Jiří Janáček ◽  
Lucie Kubínová ◽  
Ida Eržen
Keyword(s):  
Muscle Fibre ◽  
Masseter Muscle ◽  
3D Visualization ◽  
Fibre Length ◽  
Fibre Surface ◽  
Fibre Volume ◽  
Immunohistochemical Method ◽  
Muscle Fibres ◽  
Age Related ◽  
Novel Approach

The effect of ageing on the capillary network in skeletal muscles has produced conflicting results in both, human and animals studies. Some of the inconsistencies are due to non-comparable and biased methods that were applied on thin transversal sections, especially in muscles with complicated morphological structures, such as in human masseter muscle. We present a new immunohistochemical method for staining capillaries and muscle fibres in 100 µm thick sections as well as novel approach to 3D visualization of capillaries and muscle fibres. Applying confocal microscopy and virtual 3D stereological grids, or tracing capillaries in virtual reality, length of capillaries within a muscle volume or length of capillaries adjacent to muscle fibre per fibre length, fibre surface or fibre volume were evaluated in masseter muscle of young and old subjects by an unbiased approach. Our findings show that anatomic capillarity is well maintained in masseter muscle in old subjects; however, vascular remodelling occurs with age, which could be a response to changed muscle function and age-related muscle fibre type transformations.

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