3H-thymidine long survival autoradiography as a method for dating the time of neuronal origin in the chick embryo: the locus coeruleus and cerebellar Purkinje cells

J Comp Neurol. 1981 Dec 1;203(2):257-67. doi: 10.1002/cne.902030207.


Contrary to previous assumptions, we have found that a single dose of 3H-thymidine (25 muCi), injected into the yolk sac of White Leghorn chick eggs on 2 days of incubation (d.i.) only remains available for DNA-synthesizing (proliferating) cells for 48 hours following the time of injection. This finding now makes it possible to date the time of neuronal origin in the avian embryo using a single injection of isotope and a long survival time (30 days posthatch) as in mammalian studies where 3H-thymidine is only available as a short "pulse." Using this method, we have determined that neurons in the chick locus coeruleus (LC) cease proliferation on 2-6 d.i. with a peak of neuronal genesis on 3-5 d.i. In addition, neuronal genesis is not homogeneous throughout the LC cell population, but occurs in a predominantly caudorostral gradient. Conversely, the cerebellar Purkinje cells cease division on 3-8 d.i. with a peak of heavy labeling on 4-6 d.i., 1 day later than that observed in the LC.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Autoradiography
  • Cell Count
  • Cell Differentiation*
  • Cerebellar Cortex / cytology*
  • Chick Embryo
  • Locus Coeruleus / cytology*
  • Neural Pathways / cytology
  • Neurons / cytology
  • Purkinje Cells / cytology*