16 st week of pregnancy: a nervous system in full expansion

At the beginning of the fifth month of pregnancy, the fetus develops myelin, a fatty sheath that surrounds the nerves, protecting the nerve fibres and allowing exchanges between the central nervous system: the brain and spinal cord, and the peripheral nervous system.

The fetus's eyes become sensitive to light and it begins to hear sounds... It is now 20 cm long and weighs about 240 grams. In female fetuses, the fallopian tubes and uterus are in place and in male fetuses, the penis is visible.