Nancy Linn attended a memorial service for her husband, Arnold, last week. It was organized by people who never met him or knew his name and yet were connected to him in the most intimate way.

For months, medical and nursing students at Georgetown University had explored his body and those of 64 other donors in the anatomy lab. They searched for nerves, prodded muscles, laid bare major organs. They learned about disease and about complexities of the human body.

Now classes were over and the school was holding its yearly anatomical donor Mass, to say thank you. In a classroom auditorium, about 135 family members watched as a procession of 160 white-coated students walked down the aisles on either side of them. Each placed a glass-held candle on stage with a gentle clink, creating a seemingly endless chain of light.

From Linn’s front-row seat, her eyes reddened as she listened to the readings, hymns and remarks by students, a priest, a rabbi and the dean for medical education.

The donors, they said, were the students’ first patients. And students were the donors’ final caretakers.

“They knew nothing about us, and yet they dedicated their final act on this Earth to share their most intimate possession with us in the hope that we could learn from them,” said Mark Norton, 27, class president of the first-year medical students.

“Our donors taught us to celebrate life and to never forget the need for humanity and compassion in medicine — a lesson that could never be explained in any textbook or on any app.”

As the Mass drew to a close, the Rev. Salvador Jordan asked family members to step forward. Leaning on her cane, Linn, 75, joined about 20 other people, including a couple with a young boy, in the front of the room. Three students presented them each with a creamy white rose.

Her decision to donate her husband’s body had not been difficult — the couple had agreed to be organ donors. But seeing and hearing from the medical students was comforting.

“I feel so much more at ease. . . . ,” she said. “I think Arnold would be very pleased.”

Introduction to medicine

Each year, 19,000 medical students in the United States dissect cadavers as part of their introduction to medicine. It is one of the most sensitive rites of becoming a doctor because it is often the students’ first encounter with death.

Many medical schools hold some type of memorial service at the end of the school year to honor donors. At the George Washington University medical school, family members spoke, and students sang and performed original dance. The service ended with a reading of the donors’ first names and a release of butterflies.

“Gross anatomy is a very challenging course in many ways,” said Christina Puchalski, director of the university’s Institute for Spirituality and Health and one of the speakers. On the science side, students must memorize the location and function of hundreds of anatomical structures. But they also need to acknowledge their emotions.

A challenge in medical education, she said, is to help students achieve competence without losing compassion.

“Gross anatomy is the first place where students start to encounter that tension,” she said.

At Georgetown, the formal Mass has been in place for at least 25 years but has grown so large that it is now held in a classroom auditorium instead of the medical school’s small chapel.

The Mass is the coda to a year that began in late fall.

Orientation included a video of medical students describing what happens. On the first day of class, before the body bags covering the cadavers were unzipped, 196 students listened to interdenominational prayers. Letters from donors were read aloud.

The time spent on dissection varies by school. Many medical schools supplement the teaching with high-tech virtual simulations or pre-dissected bodies. Georgetown puts a heavier emphasis on students performing their own dissections; they typically spend about 100 hours in the lab. This year, course director Carlos Suarez-Quian added another hands-on component. Students had to pass a table exam after each unit, identifying specific structures on the cadaver within 20 seconds.

He noticed that students in years past were too reliant on perfect drawings they saw in textbooks or on the Web.

“That’s not who your patients are going to be,” he said.

Most donors are elderly. Disease or age often prevents them from donating organs. This year, one donor was a woman who died of breast cancer in her 40s. Another donor’s lungs were pitted black from smoking. Students don’t know the names of their donors, only age and cause of death.

Wearing blue scrubs and lab aprons, students worked in groups of five to a table, using the same body for all the labs. They started with the spine, finished with the head and neck. Only the body part being dissected was exposed; the rest was covered with cloth and black plastic, to protect the tissue from drying out. Cadavers in tan body bags meant the family wanted the remains back. Blue signified eventual burial in a common grave. The embalming process drains bodies of blood and other fluids, leaving the skin feeling hard. Students often wear two pairs of blue gloves to protect against contact with the intensely strong-smelling chemical preservatives.

‘Deep into the heart’

Class began at the end of October. By early December, they had progressed to the heart.

Instructor Suarez-Quian gave last-minute instructions. Watch out for pacemakers. Cut through the fat around the heart.

Don’t rush.

“Put your hand deep into the heart, look at it and feel it before you take the heart out,” he said.

At Table 11, students removed an unusually large heart, an indication of disease. It was the size of a small melon. “Look at the size of that aorta,” murmured Kate Wagner, 24. Their donor, an 85-year-old man, died from stroke and high blood pressure.

Her tablemate, Liz Harkin, 23, washed the dried blood clotting the internal structures. She held it under running water at a nearby sink. She was focused on her task, but she also realized she was holding a human heart in her hands.

“It’s unreal,” she said. “It’s hard to imagine.”

Finding the anatomical structure can be frustrating because every body is different. When Table 13 was looking for a nerve that controls the primary muscle used in breathing — it looks like a yellowish-white flat shoelace — one student used her iPhone, protected in a zippered plastic baggie, to consult an interactive electronic guide. But discovery is exciting.

“You almost gasp,” said John Nolan, 23, a first-year student who was also one of nine teaching assistants for the class. “You have that ‘aha’ moment, and everything starts to click. This artery is leading to here, which gives blood to this part, and you can follow it the whole way.”

Discoveries inevitably lead to more questions.

“I’m curious to know how she lived to 102,” said Bridget Kaufman, 23, bending over the chest cavity of her table’s cadaver. The heart was in good condition. Her lungs “were really clean,” she said. No cancer.

Had the woman been rich and led a pampered life, Kaufman wondered, “or did she live so long because of genetics?”

Harder for students to process were the moments when they see glimpses of nail polish, feel a strand of hair, and especially, touch fingers and hands.

Mark Real, 22, became momentarily unnerved when his hand accidently slipped into a handshake with the table’s cadaver, a 94-year-old woman. “It felt very familiar,” he said. “I stepped back for a second. I had to compose myself.”

His tablemate, Mark Mario­renzi, 24, had a similar experience when he touched her hair.

“That’s when you realize that it’s not an objective lab like we’re used to in biochemistry,” he said. “You get flooded with emotions, of your own mortality, of loss and sorrow.”

Rules for donations

Medical schools don’t pay for body donations. Georgetown’s medical school gets about 225 requests a year from people who want to donate. Some restrictions apply — no autopsies, no major surgeries, no bodies weighing more than 200 pounds. Also excluded are those outside a 50-mile radius from Georgetown, unless the family can pay for transportation. Bodies are typically used 18 to 24 months after donation. Most donors choose to remain anonymous.

All remains are cremated. About half the families request the ashes. If the families choose, they can receive the remains after the donor Mass, as was the case last week. The others are buried at Mount Olivet Cemetery in Northeast Washington in a section reserved for Georgetown’s anatomical donors.

Donors include blue-collar workers and “people of note,” said Mark Zavoyna, operations manager for the donor program. Some people choose to donate because their disease was cured and they want to give back to medical science. “They know this is a game changer for students,” he said.

Arnold Linn was a carpenter. The longtime Vienna resident was 76 when he died of pancreatic cancer in 2009. His wife, Nancy, a retired Defense Department budget analyst, wanted someone to learn from his disease.

“It’s just such a waste to put him in the ground,” she told several medical students at a reception last week after the Mass. The family had asked the hospice about body donations. From the list they received, Georgetown was the first place they called.

Impressed by Georgetown’s respect for donors and their families, she told the students that she and her youngest son David, 40, had also turned in paperwork that day to become donors.

“Hopefully, we’re not over here too soon,” she said.

After the service, Linn and David drove to the cemetery to see where the remains would be buried. Section 79 is at the back of the sprawling cemetery, near a wooden fence. An upright granite slab sits in the middle of a grassy patch. In capital letters, it reads: “In Memoriam Those who gave of themselves that others might benefit.”

It wasn’t the big ornate tombstone that Linn had imagined. But it was very nice, just the same. She stood for several minutes, looking at the spot, between two big pine trees by the back fence. She wanted to remember the landmarks so she could find her way back, after Georgetown buries her husband’s remains next month.