Former Jackson Laboratory researcher Leroy Stevens, whose work with mouse tumors led to the discovery of embryonic stem cells (ESCs), died last week (March 28) of congestive respiratory failure. He was 94.

A native of Kenmore, New York, Stevens earned an undergraduate degree from Cornell University and a PhD in embryology from the University of Rochester, both in New York. In 1953, he joined the Jackson Laboratory in Maine, where he investigated mouse models of cancer. He was promoted to the position of senior staff scientist in 1967.

In 1958, while examining a murine testicular tumor, Stevens found that part of the tumor contained many different types of tissue, including hair and teeth—a type of cancer known as a teratoma. Stevens’ further investigation of the teratoma revealed similarities to cells in the mouse embryo. When Stevens later transplanted embryonic cells into adult mice, some...

After a long career using mouse models to study cancer, Stevens retired from the Jackson Laboratory in 1989.

He is survived by two children and seven grandchildren.


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