Some brain cells have a limited ability to be replaced, especially during injury, and they do it by having undifferentiated stem cells - called embryonic stem cells - in the brain activate and mature into a specialized cell.
An undifferentiated neuroblastoma is mostly comprised of neural crest cells, which are sometimes called small round blue cells, due to a lack of cytoplasm, and a large blue nuclei.
These new neurons had developed from neural progenitor cells, a type of undifferentiated neuron akin to a stem cell, in a process scientists call neurogenesis.
There are three types of neuroblastomas, and they're categorized based on the size and shape of the tumor cells: undifferentiated, poorly differentiated, and differentiating neuroblastoma.
In frogs, gene activity showed that even when an embryo looks like an undifferentiated blob-- cells are already starting down the paths to their eventual identities.
Optimal Living Daily - Personal Development & Self-Improvement
And number two, the unconditioned self, which is our original undifferentiated nature, the timeless and unchanging essence of who we are beyond our personal story.