Key Stages of Nervous System Development in Early Embryo Growth

1. Neural Induction (Week 3):

   • A special area called the neural plate begins to form from the outer layer of the embryo.
   • About 20% of this layer helps create the neural plate.

2. Neurulation (Weeks 3-4):

   • The neural plate starts to fold to shape a structure known as the neural tube.
   • Most problems with the neural tube happen in the first month.

3. Neural Tube Closure (By Day 28):

   • The closure begins at the neck area and moves up towards the head and down towards the tail.
   • Many issues with the neural tube come from it not closing properly.

4. Neurogenesis (Weeks 5-20):

   • This is when new nerve cells, called neurons, are made from special cells.
   • By the time a baby is born, around 100 billion neurons are formed.