Abstract Background During spinal cord development. expression of chicken SEMAPHORIN6A (SEMA6A) is almost exclusively found in the boundary caps at the ventral motor axon exit point and at the dorsal root entry site. The boundary cap cells are derived from a population of late migrating neural crest cells. They form a transient structure at the transition zone between the peripheral n... https://www.roneverhart.com/Viking-K2-Slide-Gate-Opener-SPS-Model/