Myotube clusters do not bear any quantitative relation to the extent of motoneuron survival

Arumugam, T.; Sohal, G.S.

doi:10.1016/0014-4886(85)90063-9

Cited by 9 publications

(4 citation statements)

References 17 publications

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“…Thus, the overall ratio would be expected to fall somewhere between 1 and 2. A close to 1: 1 ratio has also been reported for the duck superior oblique muscle (Arumugam and Sohal, 1985).…”

Section: Number Of Myotube Clusters In Chick-quail Chimeras and Contrsupporting

confidence: 75%

“…Although a number of parameters could conceivably have been quantified (including, for example, total volume), we chose to count myotube clusters for the following reasons. First, others have found a roughly 1: 1 ratio between myotube clusters at the onset of cell death, and the number of surviving motoneurons in both chick limb (McLennan, 1982) and quail superior oblique muscle (Arumugam and Sohal, 1985). Further, it has recently been shown that motoneurons do not invade the developing hindlimb muscle masses until myotube formation occurs between stages 29-31; in fact, axon ramification within the target is temporally correlated with the formation of mature myotubes that express NCAM (neural cell adhesion molecule) on their cell surfaces (Tosney et al, 1986) and that stain for myosin ATPase (L. Landmesser, unpublished observations).…”

Section: Myotube Cluster Countingmentioning

confidence: 99%

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Cell death of lumbosacral motoneurons in chick, quail, and chick-quail chimera embryos: a test of the quantitative matching hypothesis of neuronal cell death

Tanaka¹,

Landmesser²

1986

J. Neurosci.

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The quantitative matching hypothesis of neuronal cell death was tested for the chick hindlimb by determining the relationship between myotube number at the onset of motoneuron cell death and the number of motoneurons that survive in chicks, quail, and chick-quail chimeras. Hindlimb buds, which differ in size between the 2 species, were exchanged at stages 16 1/2-19, myosin ATPase-stained myotubes in selected thigh muscles were counted during the cell death period (stages 30-34), and lumbosacral motoneurons were counted following the cell death period (stage 38). No quail motoneurons were rescued when quail cords innervated chick limbs. When chick cords innervated quail limbs, the number of surviving motoneurons was significantly decreased but not to quail values. We consider that this occurred because chicks develop more slowly than quail, and we found that transplanted chick limbs were developmentally younger than the contralateral quail limb at the onset of motoneuron cell death and contained fewer myotubes. Similarly, transplanted quail limbs contained more myotubes at the onset of cell death than normal stage 30 quail limbs. An excellent correlation was obtained during normal development of both species between the number of myotube clusters at the onset of cell death and the number of surviving motoneurons. This correlation was also observed for chick-quail chimeras, and when the data points were plotted for control chick, control quail, chick host-quail limb, and quail host-chick limb, the correlation coefficient was 0.996. This strongly suggests that some parameter closely related to myotube number limits the number of motoneurons that will survive. A proposal consistent with our observations is that motoneuron survival is dependent on the uptake of a myotube-derived trophic factor that can only be taken up at synaptic sites and that the number of such sites is limited and directly related to myotube number. In conclusion, our observations strongly support a quantitative-matching component in the process of neuronal cell death. However, since we were unable to rescue any neurons, we cannot exclude the possibility that some proportion of neurons normally dies for reasons other than peripheral competition.

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“…Thus, the overall ratio would be expected to fall somewhere between 1 and 2. A close to 1: 1 ratio has also been reported for the duck superior oblique muscle (Arumugam and Sohal, 1985).…”

Section: Number Of Myotube Clusters In Chick-quail Chimeras and Contrsupporting

confidence: 75%

Section: Myotube Cluster Countingmentioning

confidence: 99%

Cell death of lumbosacral motoneurons in chick, quail, and chick-quail chimera embryos: a test of the quantitative matching hypothesis of neuronal cell death

Tanaka¹,

Landmesser²

1986

J. Neurosci.

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“…A similar correlation has been found for limb motoneurons and myotubes in frog embryos (McLennan, 1988). By contrast, studies of motoneurons innervating non-limb muscles have not found such correlations (Arumugam and Sohal, 1985). Even if myotubes numbers are assumed to be limiting in motoneuron survival, it is not clear what actually makes them limiting.…”

Section: Naturally Occurring Motoneuron Deathmentioning

confidence: 97%

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

1990

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Thoracic spinal cord transplanted to the lumbar region at the time of neural tube closure in the chick embryo survives and initially differentiates normally similar to in situ thoracic cord. Normal numbers of motoneurons are produced that innervate the host hindlimb musculature. In control thoracic cord approximately 70% of the motoneurons are lost by normal cell death between embryonic day (E) 6 and E11-E12. By contrast, the transplanted thoracic cord loses only about 30% of the motoneurons during this period. Transplantation of one hindlimb to the thoracic region also reduces the normal loss of in situ thoracic motoneurons. We conclude that some factor(s) associated with the increased target size provided by the hindlimbs promotes the survival of thoracic motoneurons. In contrast, by E16-E18 motoneuron numbers in the thoracic transplants decrease to below control levels. Dorsal root ganglion cells in the transplant were also initially increased (on E8) but later decreased to below control values. Hindlimb muscles innervated by thoracic motoneurons in the transplant also differentiated normally up to E10 to E12. Myotube size and numbers, muscle size and myotube types (fast versus slow) all developed normally in several thoracically-innervated hindlimb muscles. However, beginning on E14 myotube numbers and muscle size were markedly decreased resulting in muscle atrophy. Injections of horseradish peroxidase (HRP) into the thoracic transplants labelled neurons in the host spinal cord and brainstem rostral to the transplant thereby indicating an anatomical continuity between host and transplant neural tube. Injections of HRP into specific thoracically innervated hindlimb muscles on E8 labelled distinct pools of motoneurons in the transplants.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…While some natural variation in the adult numbers of neurons in a variety of cell populations from other vertebrate species is present (e.g., in amphibians, Davis et al, 1983;Sperry and Grobstein, 1983;Kollros, 1984: Farel, 1987Kollros and Thiesse, 1988; in birds, Hamburger, 1975;Carr, 1984;Arumugam and Sohal, 1985;Sohal et al, 1985;in mammals, Ebbesson, 1968;Ygge e t al., 1981;Purves et al, 1986; for a recent review see Williams and Herrup,7 988), the magnitude of the differences observed in Xenopus is quite striking.…”

mentioning

confidence: 97%

Variation and symmetry in the lumbar and thoracic dorsal root ganglion cell populations of newly metamorphosed xenopus laevis

Sperry

1990

J of Comparative Neurology

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The sizes of the lumbar and thoracic dorsal root ganglion cell populations in normally developing newly metamorphosed Xenopus laevis were measured in order to determine whether these neuron populations have the same characteristics as the hindlimb motoneuron population (i.e., large individual as well as sibling group differences, striking bilateral symmetry, and a rough correspondence between neuron number and body size that suggests some peripheral control of cell number during normal development (Sperry, J. Comp. Neurol. 264:250-267). Among animals from three sibling groups, the total numbers of thoracic and lumbar ganglion cells are highly variable and symmetrical, although symmetry is not uniformly present at the level of individual ganglion pairs. Significant sibling group differences in neuron number are also present. Metamorphic body size and cell number in the thoracic but not in the lumbar ganglia are significantly correlated. The motoneurons innervating the hindlimbs were also counted and measured in the same animals. While variable as well as symmetrical, motoneuron number and metamorphic body size are correlated in only two of the three sibling groups. Interestingly, the numbers of motoneurons and lumbar ganglion cells, two populations of neurons whose sizes one might predict would be significantly correlated in normally developing animals, are not correlated. The relationship between these observations and currently held views concerning how neuron numbers might be controlled during normal development is discussed.

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Myotube clusters do not bear any quantitative relation to the extent of motoneuron survival

Cited by 9 publications

References 17 publications

Cell death of lumbosacral motoneurons in chick, quail, and chick-quail chimera embryos: a test of the quantitative matching hypothesis of neuronal cell death

Cell death of lumbosacral motoneurons in chick, quail, and chick-quail chimera embryos: a test of the quantitative matching hypothesis of neuronal cell death

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

Variation and symmetry in the lumbar and thoracic dorsal root ganglion cell populations of newly metamorphosed xenopus laevis

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