Factors That Influence the Phenotypic Expression of Genetically Normal and Dystrophic Muscles *

In vivo proton spin‐lattice relaxation times of normal and dystrophic muscles

“…Hazlewood et al (29) have shown in other species of animals that the skeletal water proton relaxation times are longer in immature muscles and shorten with maturation. This conclusion is also consistent with the earlier studies on the age-dependent behavior of the normal and dystrophic muscles (5,13,(30)(31)(32)(33)(34)(35) which established the relationship between the embryonic and dystrophic muscles. The studies of John (36) and Marechel et al ( 3 7 ) on rodent models showed that the dystrophic and regenerating muscles contained fetal and neonatal myosin isozymes.…”

“…The histologic and histochemical resemblance of the chicken dystrophic muscles to the immature muscles has been reviewed by Cosmos et af. (13) and Wilson et af. (5).…”

In - vivo proton spin lattice relaxation times in normal and dystrophic muscles

“…Hazlewood et al (29) have shown in other species of animals that the skeletal water proton relaxation times are longer in immature muscles and shorten with maturation. This conclusion is also consistent with the earlier studies on the age-dependent behavior of the normal and dystrophic muscles (5,13,(30)(31)(32)(33)(34)(35) which established the relationship between the embryonic and dystrophic muscles. The studies of John (36) and Marechel et al.…”

Development and survival of thoracic motoneurons and hindlimb musculature following transplantation of the thoracic neural tube to the lumbar region in the chick embryo: Anatomical aspects

“…However, our experimental paradigm differs from postnatal denervation/cross reinnervation studies in that embryonic hindlimb musculature in our experimental embryos had never experienced their own appropriate innervation prior to receiving the thoracic input. Although numerous studies (Buller, Mommaerts, andSeraydarian, 1960: Cosmos, Butler, Allard, andMazliah, 1979;Close, 1965;Salmons and Streter, 1976) have examined the events subsequent to muscle cross-innervation carried out postnatally, very little information is available on the effects of foreign inner-vation of skeletal muscle initiated at the very onset of normal innervation in the embryo. The early spinal cord transplantation studies reported on here and in the following companion paper (O'Brien et al, 1990) were designed to provide a model for addressing a number of fundamental issues concerning development of the spinal neuromuscular system: will thoracic neural tube developing in the lumbar region differentiate its normal region-specific morphology; will the transplanted cord form connections (motor and sensory) with the host nervous system; will thoracic motoneurons located in a foreign environment survive and innervate a peripheral target that they normally never encounter; is motoneuron survival altered quantitatively as a result of contacting a novel target; are contacts between thoracic neural tube and hindlimb muscles functional and if so is the function appropriate for normal thoracic cord or normal lumbar cord; if functional contacts are established, are these stabilized and…”

“…By contrast. cross-reinnervation studies in postnatal animals demonstrate that muscle phenotype can be altered by foreign motor innervation (Cosmos et al, 1979). Consequently, it was of interest to determine the muscle fiber type differentiation in thoracically-innervated hindlimb muscles which exhibit an altered EMG activation pattern (O'Brien et al, 1990).…”