My PhD thesis is devoted to development of adrenal medulla (AM) of adrenal gland, Zuckerkandl organ (ZO) and the area around these two organs that might become malignant. I focus mainly on Schwann cell precursor cells (SCPs) and its derivatives, trying to answer next questions: how do cells make their choice which differentiating path to choose? What does the mechanism underlie in disappearing of ZO? Is there any common with the way some types of neuroblastoma dissolve in children? That puzzles me a lot and gives an inspiration to dig deeper.