Explain why it is wrong and rewrite them in a more correct form.  Sensory tracts projecting into the ventral horn of the spinal cord are myelinated by oligodendrocytes; their speed of transmission is therefore slower than that within grey matter. In contrast, the motor nerves projecting into the dorsal horn of the spinal cord are myelinated by Schwann cells, thereby increasing their speed of transmission, relative to that of grey matter.