A rare, primitive, rapidly growing intracranial neoplasm thought to originate from the cells of the embryonic medullary canal and hence included with ependymoblastomas by some neuropathologists; ganglion cells and astrocyte maturation have also been reported. Tumors that occur in the ciliary body are referred to as embryonal medulloepitheliomas. [medullo- + epithelium + -oma, tumor]