Stem cells, neural regeneration, and brain cancers


Amazingly, a decapitated planarian can regenerate an entire brain, head and eyes within 7 days. Shown below is a seven-day head regeneration series taken from Newark and Sanchez-Alvarado 2002. The other panels show in situ hybridizations for common neurotransmitters in planarians. Despite a simple morphology, planarian brains are highly complex structures, composed of thousands of neurons with specific cell identities. We are interested in two main questions regarding brain regeneration.

  1. How are planarian brains patterned in time and space during regeneration to make all neural cell types in their proper ratios?
  2. What is the cellular lineage by which a stem cell can make a specific neural cell type?

A hypothesized lineage example is shown in the middle.