Human ecchordosis physaliphora and chick embryonic notochord. A comparative electron microscopic study.

The ecchordosis physaliphora, a small gelatinous mass attached to the midline of the clivus, is characterized ultrastructurally by glycogen-laden intracytoplasmic vacuoles, focally distended endoplasmic reticulum and perinuclear cisterns with cytoplasmic invaginations, large clusters of granular endoplasmic reticulum interdigitating with mitochondria, and an abundant extracellular space. These morphologic features are also present in the 9-day embryonal chick notochord and the human chordoma and serve to reaffirm the derivation of the ecchordosis and chordoma from notochordal rests.