Miniature brain discovered in girl's ovary

摘要

A tumour containing a small brain has been found growing on the ovary of a 16-year-old girl in Japan. The 10-centimetre-wide tumour was discovered when the girl had surgery to remove her appendix. Inside the tumour, doctors found clumps of hair, and a 3-centimetre-wide brain-like structure covered by a thin plate of skull bone. Closer analysis revealed that it was a small version of a cerebellum, which usually sits underneath the brain's two hemispheres. A mass on one side resembled a brainstem - the structure that normally joins to the spinal cord.