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