Clinical Correlate

Primordial Germ Cells (PGCs) and Teratomas

Teratomas are tumors of disputed origin that often contain a variety of tissues, such as bone, hair, muscle, gut epithelia, and others. It is thought that these tumors arise from a pluripotent stem cell that can differentiate into any of the three germ layers or their derivatives.

Primordial Germ Cells Yolk Sac
Figure 1.1 An embryo at the end of the third week, showing the position of primordial germ cells in the wall of the yolk sac, close to the attachment of the future umbilical cord. From this location, these cells migrate to the developing gonad.

Some evidence suggests that PGCs that have strayed from their normal migratory paths could be responsible for some of these tumors. Another source is epiblast cells migrating through the primitive streak during gastrulation (see page 80).

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