Final answer:
During spinal cord development a Shh concentration gradient is used to determine cell types along the ventral to dorsal direction.
Step-by-step explanation:
During the development of the spinal cord, a Shh concentration gradient is indeed used to determine which cell types form along the ventral to dorsal direction. Shh or Sonic Hedgehog is a signaling molecule that plays a crucial role in the patterning of the spinal cord. it is secreted by the notochord and floor plate cells, creating a gradient that guides the differentiation of different cell types.
High Shh concentrations at the ventral side induce the formation of motor neurons, while lower concentrations at the dorsal side lead to the development of sensory neurons.