The thoracic sympathetic neurons of the chick: normal development and the effects of nerve growth factor

Histol Histopathol. 1986 Oct;1(4):315-22.


The generation and degeneration of sympathetic neurons in the third thoracic ganglion (segment 19) of the chick were studied between embryonic days (E) 7-18 using 3H-Thymidine autoradiography and routine cell counts. Cumulative radiolabelling experiments indicated that few sympathetic neurons were generated on E6-7. 10% of the sympathetic neurons were generated on E8 and a further 20% on E9. The final 70% of neurons completed the mitotic cycle between E10-12. Cell counts demonstrated that the neuronal population increased from 10,166 +/- 423 (mean +/- SEM) to 22,291 +/- 767 between E8-10 and remained stable up to E14. The population subsequently declined by 37%, to 14,157 +/- 831, by E18. Pyknotic neurons were found at all stages of development, but were most apparent between E7-15. The effects of Nerve Growth Factor (NGF) on the number of both surviving and pyknotic neurons in the ganglion were also examined. E9 embryos treated with NGF from E5-8 showed a 57% increase in the number of sympathetic neurons. This increase therefore occurred prior to the decline in neuronal number and was not accompanied by a decrease in the number of visibly pyknotic neurons. It is therefore possible that early NGF treatment increases the number of sympathetic neurons through a mechanism other than the attenuation of cell death.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Count
  • Cell Death / drug effects
  • Cell Division / drug effects
  • Chick Embryo
  • DNA / biosynthesis
  • Nerve Growth Factors / pharmacology*
  • Neurons / drug effects
  • Sympathetic Nervous System / drug effects
  • Sympathetic Nervous System / embryology*
  • Thorax


  • Nerve Growth Factors
  • DNA