What is the structure in mammalian embryos that develops to brain and spinal cord?

The structure in mammalian embryos that develops to brain and spinal cord is the Neural tube.

During gestation, part of the ectoderm folds inward to form a tube containing fluid, the neural tube. This structure gives rise to the central nervous system, the most complex system of organs in the entire organism. It can be divided into anterior (rostral) and posterior (caudal) parts – the primary brain vesicle and the spinal cord, respectively. The primary brain vesicle consists of three regions, which then further subdivide and differentiate.