Main event: growing head.
• The head is growing rapidly, and the brain is developing, and the structures that form it are already visible on ultrasound.
• In the gums, the laying of teeth begins.
• Internal organs continue to form: the rectum, bladder, etc. The bronchi and lobes of the lungs develop.
• The brush begins to form, the rudiments of fingers are visible.
• Blood vessels from the embryo join with others in the developing placenta to form the umbilical cord. The embryo is firmly attached to the wall of the uterus.
• The skin of the embryo is thin, blood vessels are clearly visible through it.
Embryo dimensions: 10 - 15 mm in length.