Principal neurons of the lumbar sympathetic ganglia increase in number with body size.
Neuron number appears to be matched to body size during early development by the modulation of the processes of proliferation and naturally occurring cell death. However, body size increases rapidly as the juvenile becomes an adult, long after these processes cease to operate. The present study shows that principal neurons of lumbar sympathetic ganglia increase in number four- to fivefold during postmetamorphic life of the bullfrog. Rana catesbeiana. This increase in neuron number cannot be attributed to either counting error or selection bias and was associated with greater innervation of particular hindlimb targets, as demonstrated by retrograde labeling with horseradish peroxidase. Injection of [3H]thymidine (a marker of DNA synthesis) every third day for 20-22 weeks failed to provide evidence of neuron proliferation, although, on the basis of changes in body length during this period, substantial numbers of neurons likely were added. These results combined with previous studies of hindlimb motor and sensory neuron addition are consistent with the hypothesis that the population of sympathetic neurons is augmented by late differentiation of existing precursor cells.
St Wecker
P G
PG
Department of Physiology, University of North Carolina School of Medicine, Chapel Hill 27599, USA.
Baek
J K
JK
Farel
P B
PB
D000818:Animals; D001824:Body Constitution / Q000502:physiology*; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology; D016922:Cellular Senescence / Q000502:physiology; D005728:Ganglia, Sympathetic / Q000166:cytology*; D006735:Horseradish Peroxidase; D008161:Lumbosacral Region; D010641:Phenotype; D011892:Rana catesbeiana / Q000033:anatomy & histology* / Q000254:growth & development; D015203:Reproducibility of Results
D006735:Horseradish Peroxidase