Henrichs’s kidneys were failing, and he was in need of a transplant. After nearly 40 family members and friends were tested as possible donors, only one person turned out to be a perfect match: Ziegler.

There was never any question in Ziegler’s mind about whether she’d do it.

“I just immediately knew that it was going to happen,” she said. “Bill and I grew up together, we had two children together. And I knew that my children and grandchildren needed their father and grandfather in their lives.”

So on Oct. 16, more than four decades after they said “I do,” she and Henrichs, 62, were wheeled into an operating room at the Mayo Clinic in Rochester, Minn., and one of Ziegler’s healthy kidneys was removed and given to her ex-husband. The transplant went smoothly, with Ziegler going home after three days and Henrichs after two weeks of tests and observation.