ST. LOUIS • A mother's stilled voice on a CD. A can of Bud Light in memory of happy hoistings.

Those are the sorts of personal touches that come and go at a common burial plot in Sts. Peter and Paul Cemetery in south St. Louis. Beneath its grass are the commingled ashes of more than 12,000 people who have donated their bodies to St. Louis University School of Medicine.

Two dozen arborvitae (tree of life) evergreens, planted in a crescent, provide a touch of refuge for the small nook of land amid a busy neighborhood. There are four small marble benches, but no list of donors' names at the site. A single stone thanks them for their part in the "advancement of medical science."

Some time around Easter, medical school personnel will hold a quiet burial ceremony for the ashes of another 200 or so donors. The medical school does that twice each year, without fanfare. Family members sometimes place anonymous mementos, such as the CD and the beer can. Others put Christmas ornaments on the trees, or leave flowers or teddy bears. Once each month, cemetery workers sweep the place clean of all the personal touches, just as they do at all burial sites.

There's nothing particularly striking about the site, only a short walk from Loughborough Avenue. Families and caretakers tend to like it that way.

"It's a peaceful place, a reverential place," said Carol Liebler of Florissant, whose parents' ashes are there. "It gives me a final place I can visit, and time to ponder that my parents' last gift maybe produced a great doctor out there somewhere."

Liebler, 69, visits two or three times each year. She said she plans to donate her remains as there as well,

About 1,000 of the donors' names are inscribed on a granite memorial 600 yards away, near the cemetery entrance at 7030 Gravois Avenue. Among them are Liebler's parents, Mary Ann and Cyril Jacobsmeyer, who died in 2003 and 2005, respectively. That memorial, which costs about $200 to add a name, lists less than 10 percent of the donors.

St. Louis University's medical school has used the burial place since 1964. Margaret Cooper, a professor of anatomy and director of the donor program, said about 375 to 400 people now donate their bodies annually to the medical school. Those numbers were lower in the early years.

The school is one of three local institutions that receive donations of bodies for instruction. The Washington University School of Medicine, which gets about 280 donors annually, periodically spreads ashes in the woods at its Tyson Research Center in southwest St. Louis County. There's a clearing set aside for reflection, and families can call ahead to make visits, said Dan Loesche of the Washington University program. (Among its donors was Liebler's husband, Bernard, who died in 1991.)

Logan College of Chiropractic in Chesterfield receives about 50 donors annually, said spokesman Tom Keller. The college returns ashes to a family on request, or inters them at a single site at Holy Cross Cemetery in Ellisville.

All three institutions require that donors agree to cremation.

St. Louis University's medical school gathers ashes in 20 or so heavy cardboard boxes before heading down to the cemetery for the twice-annual burials. Students and instructors represent the school. A priest says prayers. Then the cemetery crew does its work.

The medical school holds an annual public memorial service on or near campus for the families of donors. It does not, and will not, let anyone know when the ashes are interred.

All Cooper will say is that burials take place around Christmas and Easter.

If donors' families request it, the school will inform them afterward that the burial has taken place.

Cooper said the site doesn't list names for a reason.

"We believe the anonymity adds to the serenity of the place," she said. "Our donors are fantastic people who gave the ultimate gift to educate our future physicians and health professionals.

"The (cemetery) site is there so families can have a place to reflect and say a prayer. I love it when people leave things like the beer can. It's very touching."