In the human brain, development of structural connectivity starts during the early fetal period, and progresses in a complex but sequential way, until all major axonal pathways become established in the preterm period, as outlined by post mortem and in vivo studies based on histological stainings and MRI. Through the myelination process, these networks further mature and refine after term birth until the end of adolescence, leading to the emergence of mature patterns of functional connectivity in the course of development.