11/27/2021
Awesome photo of the brain beginning to
develop in the human embryo.
The brain grows at an amazing rate during development. At
times during brain development, 250,000 neurons are added
every minute! At birth, almost all the neurons that the brain
will ever have are present. However, the brain continues to
grow for a few years after birth. By the age of 2 years old, the
brain is about 80% of the adult size.
You may wonder, "How does the brain continue to grow, if
the brain has most of the neurons it will get when you are
born?". The answer is in glial cells. Glia continues to divide
and multiply. Glia carries out many important functions for
normal brain function including insulating nerve cells with
myelin. The neurons in the brain also make many new
connections after birth.
The nervous system develops from embryonic tissue called
the ectoderm. The first sign of the developing nervous
system is the neural plate that can be seen at about the 16th
day of development. Over the next few days, a "trench" is
formed in the neural plate - this creates a neural groove
By the 21st day of development, a neural tube is formed
when the edges of the neural groove meet. The rostral (front)
part of the neural tubes goes on to develop into the brain and
the rest of the neural tube develops into the spinal cord.
Neural crest cells become the peripheral nervous system.
At the front end of the neural tube, three major brain areas
are formed: the prosencephalon (forebrain), mesencepalon
(midbrain) and rhombencephalon (hindbrain). By the 7th
week of development, these three areas divide again. This
process is called encephalization.
Here's a nice illustration of the growing process:
htto://bit.Iv/1RltaGo
Photo and content credits;
