The transfer of endosomes carrying TrkA anterogradely and retrogradely in neurons . TrkA is transported anterograde from somatic cells to axon growth cones via the exocytosis or transcytosis pathway . NGF/TrkA is endocytosed and incorporated into endocytic vesicles. Endocytosis might take place within the cell body or at the axon tip. It is transported to somatic cells for recovery or retrograde transport . After binding and activation by target-derived NGF, TrkA is retrogradely trafficked from the axon growth cone to the cell body . TrkA endosomes associate with actin regulatory proteins and mature into signaling endosomes with transport capacities. After that, the signal begins to pass the plasma membrane and enter the intracellular cytoplasm. Retrograde transport is the method by which signaling endosomes carry NGF/TrkA. The signaling molecules are carried down long axons to reach the cell bodies and dendrites .