Tritiated Thymidine Autoradiography:
neuroblasts in the ventricular zone will divide, differentiate into neurons, and migrate to specific areas in the brain
during cell division, DNA is being synthesized
3H-thymidine will be incorporated into newly synthesized DNA
if 3H-thymidine is injected on day 18 of gestation, then all neurons “born” on day 18 will have radioactive DNA with cell’s nucleus
can identify “birthdate” of neurons by exposing brain sections to X-ray film or by dipping sections in a photographic emulsion
- radioactivity will expose the photographic emulsion
- can learn: how many neurons are born on a given day, where they migrate, and if they survive into adulthood