The embryo is about the size of a small bean – about ½ an inch long this week. If you could reach the baby and try to tickle its little nose it would jump and respond to your touch now!
The head is very oversized and all of the facial features are becoming more defined. The eyes are formed and sealed shut until the 28th week of pregnancy. Eyelids are beginning to form. Ear indentations and the semicircular canals begin to form in the inner ear to help with balance. The brain is close to completion at this point and is growing at an amazing rate.
The buds that will become the arms and legs are very noticeable now. Hands and feet look like paddles.
This is the point where the critical development of the arms ends, but the hands will continue to develop over the next few days, although they have indentations where the fingers will separate now. The critical development of the legs will end soon, but the knees and ankles can be distinguished by small dots on the legs and the toes are notched and toenails are beginning to appear.
You can’t tell the difference from boys and girls yet by sight, but the gonads are formed. The gonads are either the testes in the male, or the ovaries in the female. These will be responsible for producing sperm and ova, but also secrete hormones and are considered endocrine glands.
The heart is beating at around 150 beats per minute, about twice your heart rate, and will continue to do so throughout your pregnancy. The kidneys produce urine for the first time. Your baby will rapidly go through three sets of kidneys, the second set will form this week. When bone marrow forms later, it will take over the production of red blood cells, but for now the liver is working over time to produce these.