The College of Physicians of Philadelphia Digital Library

Placental Corrosion Specimen with Twin

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Placental Corrosion Specimen with Twin




This double placenta nourished a pair of twins during pregnancy, but something went wrong. The placenta, an organ that develops in the uterus during pregnancy, provides nutrients and oxygen to a developing fetus through the arteries and vein in the umbilical cord. The human navel or belly button, the scar left after the umbilical cord detaches, is a permanent reminder of the months spent in the womb.

The mother of these twins had hydramnios (amniotic fluid disorder), a condition that occurs in about 1–4% of pregnancies, more frequently with twins or multiple births. The amniotic sac filled with fluid surrounds the fetus, forming a protective cushion. The fetus moves around in the amniotic fluid and even “breathes” the liquid, which helps its lungs develop. If there is too much or too little fluid, however, the fetus or fetuses may not grow normally.

In this case, one fetus literally crowded out the other, which stopped developing at four months gestation. The remaining twin, a boy, developed fully and was born normally. When the placenta was expelled after birth, the tiny, compressed body of the second fetus was revealed. As the old catalogue card for the specimen notes, “the struggle for existence . . . began in the womb.”

The skull collection of Austrian anatomist Joseph Hyrtl, MD (1810–1894), is one of the highlights of the Mütter Museum. Hyrtl also studied placentas for clues about fetal development. This specimen resembles a wax model because it is partly made of wax. To create a corrosion specimen, the preparator injected liquid wax into blood vessels. After the material hardened, the preparator applied acid to corrode or “burn” away the surface of the blood vessels, then painted the wax casts to look lifelike. Here, red pigment (now faded) marks the arteries that took oxygen-rich blood from the placenta to the fetus, and blue shows the veins that carried oxygen-depleted blood back to the placenta. Acid also removed the flesh of the remaining fetus, leaving only the skeleton. Hyrtl was a highly skilled anatomical preparator, expert in the corrosion process.


Digitized by the Mütter Museum of The College of Physicians of Philadelphia


19th Century


Joseph Hyrtl, MD, Donor






19th Century

Original Format

Human tissue and bone, wax, pigment, wood base


“Placental Corrosion Specimen with Twin,” The College of Physicians of Philadelphia Digital Library, accessed May 16, 2021,