Dismiss Modal

Definition

Anatomy: Fetus in Utero

Choose a preferred language

Amniotic sac. A thin-walled sac that surrounds the fetus during pregnancy. The sac is filled with liquid made by the fetus (amniotic fluid) and the membrane that covers the fetal side of the placenta (amnion). This protects the fetus from injury. It also helps to regulate the temperature of the fetus.

Anus. The opening at the end of the anal canal.

Cervix. The lower part of the uterus that extends into the vagina. The cervix is made up of mostly fibrous tissue and muscle. It is circular in shape.

Fetus. An unborn baby from the 8th week after fertilization until birth.

Placenta. An organ shaped like a flat cake. It only grows during pregnancy. The fetus takes in oxygen, nutrients, and other substances from the placenta and gets rid of carbon dioxide and other wastes.

Umbilical cord. A rope-like cord connecting the fetus to the placenta. The umbilical cord contains 2 arteries and a vein. It carries oxygen and nutrients to the fetus and waste products away from the fetus.

Uterus. The uterus, or womb, is a hollow, pear-shaped organ in a woman's lower stomach between the bladder and the rectum. It sheds its lining each month during menstruation. A fertilized egg (ovum) becomes implanted in the uterus, and the fetus develops.

Vagina. The part of the female genitals behind the bladder and in front of the rectum that forms a canal. This extends from the uterus to the vulva.

Side view cross section of woman's pelvis with fetus in uterus.

Featured in

© 2000-2025 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
Related Articles
Read more →
OB/GYN
Anatomy of the Uterus

The uterus is part of the female reproductive system. You may know it as the womb.

Read more →
OB/GYN
Anatomy of Female Pelvic Area

The female pelvic area contains a number of organs and structures: the endometrium, uterus, ovaries, cervix, vagina, and vulva.

Read more →
OB/GYN
Labor and Childbirth: Your Body Prepares

Learn about the physical changes that often signal that your baby will soon be born.

Read more →
Heart Health
Fetal Circulation

Through the blood vessels in the umbilical cord, the fetus receives all the necessary nutrition, oxygen, and life support from the mother through the placenta.