Embryo Project Encyclopedia
The Embryo Project Encyclopedia (https://embryo.asu.edu) is an open-access digital encyclopedia devoted to recording and contextualizing the science of embryos, development, and reproduction. The collection of documents, images, and multimedia housed here serves as the Encyclopedia's permanent archive.
Jane Maienschein, ASU University Professor, Regents Professor, and Director of the Biology and Society Program, started the Embryo Project Encyclopedia in 2007 with support from the National Science Foundation.
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- All Subjects: Pregnancy
- Creators: DeRuiter, Corinne
Fetus in fetu is a rare variety of parasitic twins , where the developmentally abnormal parasitic twin is completely encapsulated within the torso of the otherwise normally developed host twin. In the late eighteenth century, German anatomist Johann Friedrich Meckel was the first to described fetus in fetu, which translates to “fetus within fetus.” Fetus in fetu is thought to result from the unequal division of the totipotent inner cell mass , the mass of cells that is the ancestral precursor to all cells in the body. The unequal division is thought to occur during the formation of the blastocyst, which can also result in parasitic and conjoined twins . Fetus in fetu represents a developmental anomaly that has prompted developmental biologists to further examine the mechanisms for how twins arise.