The two prolongations of spinal ganglia neuroblasts: an ultrastructural study during chick embryo development

Peripheral and central prolongations of chick embryo spinal ganglia neuroblasts were studied and compared at an ultrastructural level during development. Important differences in the terminal tracts of the prolongations and their endings were demonstrated. The possibility of environmental influences being responsible for structural differences in the two prolongations is suggested. It was not possible, at any stage of development, to demonstrate significant polarization of any cytoplasmatic structure in the emerging cones.