The Niswander lab has pioneered a new approach to visualize the forming brain and spinal cord in a living mouse embryo. The brain and spinal cord start from a flat sheet of cells that rises up and seals together to form a simple tube. This video, of <6 hours of development, shows the forming brain region.
The equivalent process of neural tube closure in the human embryo occurs between weeks 3-4 of gestation.
Defects in the process of neural tube closure cause neural tube defects such as spina bifida and anencephaly. Neural tube defects are the second most common birth defect in humans.
Video from Massarwa and Niswander, Development 2013.