human embryos

The temperature in a cryogenic tank at a fertility clinic in suburban Cleveland fluctuated earlier this month, rendering some 4,000 eggs and embryos nonviable.

Ohio Fertility Clinic Says 4,000 Eggs And Embryos Destroyed When Freezer Failed

Laurel Wamsley

The hospital system said its investigation suggested that the problems may have been caused by human error, mechanical failure or both. "We failed our fertility clinic patients," said its CEO.

After a cryogenic tank like the one in this file photo lost a great deal of liquid nitrogen, a fertility clinic began the process of determining the damage to stored embryos and eggs.

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Fertility Clinic Says Failure May Have Damaged Thousands Of Eggs And Embryos

Bill Chappell

The problem hit a San Francisco clinic on March 4 — the same day that a similar cryogenic tank failure was reported in Cleveland.

This sequence of images shows the development of embryos formed after eggs were injected with both CRISPR, a gene-editing tool, and sperm from a donor with a genetic mutation known to cause cardiomyopathy.

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Exclusive: Inside The Lab Where Scientists Are Editing DNA In Human Embryos

Rob Stein

NPR gets exclusive access to a lab in Portland, Ore., where scientists have begun editing the DNA in human embryos to try to prevent genetic diseases.