Developmental changes in contraction time and muscle fibre pattern of fast and slow muscles

1973 ◽  
Vol 29 (4) ◽  
pp. 435-436 ◽  
Keyword(s):  
Muscle Fibre ◽  
Developmental Changes ◽  
Contraction Time ◽  
Fast And Slow Muscles ◽  
Fibre Pattern

Muscle fibre types in the reduced forelimb and enlarged hindlimb of the quokka (Setonix brachyurus, Macropodidae)

2016 ◽  
Vol 64 (4) ◽  
pp. 277 ◽  
Author(s):  
A. Casinos ◽  
N. Milne ◽  
F. K. Jouffroy ◽  
M. F. Médina
Keyword(s):  
Muscle Fibre ◽  
Knee Extensors ◽  
Muscle Fibre Types ◽  
Type I ◽  
Plantar Flexors ◽  
Hind Limbs ◽  
Anatomical Adaptations ◽  
Fast Twitch ◽  
Fibre Pattern ◽  
Gastrocnemius Lateralis

The quokka (Setonyx brachyurus) is restricted to two offshore islands and small isolates on the mainland of south-western Australia. It displays a tendency to saltatorial locomotion and moves at speed by bipedal hopping, although it also uses its forelimbs at low speed. Its bipedal adaptation involves enlarged hind limbs, with elongated feet. The fibre type distribution of the elbow and knee extensors, and the ankle plantar flexors, in comparison with two eutherians, the quadrupedal rhesus monkey, as a locomotor generalist, and the jerboa, a small eutherian hopping species morphologically similar to the quokka, were studied. The quokka’s forelimb showed the same characteristics as that of the jerboa, lacking the fatigue-resistant Type I fibres that are used to sustain posture. As in the jerboa, the gastrocnemius lateralis was the muscle head with the highest proportion of fast twitch fibres. Muscular fibre pattern is not identical in the quokka and the jerboa hindlimb, but it appears that both species have similar anatomical adaptations to saltatorial locomotion. Differences in muscle fibre proportions could be due to several factors including, resting posture, body size and the propensity for elastic energy storage, the burrowing behaviour of the jerboa, but also to phylogenetic constraints where the adaptation to hop on the hindlimbs is a shared behaviour of the Macropodoidea (jerboas are the only Dipodidae to have elongated hindlimbs).

Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

1983 ◽  
Vol 41 ◽  
pp. 518-519
Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee
Keyword(s):  
Crystal Structure ◽  
Crassostrea Virginica ◽  
Crystal Orientation ◽  
Developmental Changes ◽  
Gastrula Stage ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Stages Of Growth ◽  
Early Stages ◽  
Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

Developmental Changes in Anxious Children's Cognitions: Implications for research and clinical practice

2013 ◽  
Author(s):  
Melissa E. Tamas ◽  
Robert D. Friedberg ◽  
Rosa M. Poggesi ◽  
Micaela Thordarson ◽  
Lisa C. Hoyman ◽  
...  
Keyword(s):  
Clinical Practice ◽  
Developmental Changes
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