Marshall L. Rennels, a retired University of Maryland medical school research scientist and professor, died of cancer yesterday at his home in Elkridge. He was 65.
Dr. Rennels, who devoted most of his career to the study of the brain, showed through his groundbreaking research how the body used the pulsation of arteries to force spinal fluid through brain tissue. He served as acting chairman of the university's anatomy department and as director of the medical and doctorate programs until his retirement in 2002.
Born in Sergeant Bluff, Iowa, the son of a meteorologist, Dr. Rennels grew up surrounded by scientists. Students and colleagues said he never lost his Midwestern drawl and wry humor. Many praised his teaching skills.
"His laconic presentations meshed perfectly with the intricate and quasi-magical complexities of the organ he studied," said Jon Franklin, a friend and former Evening Sun reporter.
Dr. J. Tyson Tildon, professor emeritus in the university's school of medicine, worked with Dr. Rennels for 30 years.
"He would stand in front of a class of 150 students, and there was an electricity, an intensity, some indefinable thing that allowed the information to flow from him to his students," Dr. Tildon said.
Dr. Gerald Cole, adjunct professor at the university, recalled the 28 awards students bestowed on the teacher who helped them pass their most difficult courses. Dr. Rennels was chosen to receive the first Founders Day Award in 1996. The university has established an award in Dr. Rennel's name that will be given annually to a student in neuroanatomy.
"Something about teaching is intangible," Dr. Cole said. "Marshall had style and data-based information that he presented in a fascinating way. He also published numerous articles in the field of neuroscience in various medical journals."
Dr. Rennels graduated from Eastern Illinois University and received his doctorate from the University of Texas at Galveston in 1966. He came to the University of Maryland soon after.
In 1971, he married Margaret Baker, a physician and fellow medical researcher who is now professor of pediatrics at the university.
"He was a devoted educator who was always interested in people," his wife said. "He loved learning about them and talking to them."
Dr. Anne Hirshfield, assistant dean for research at the University of Maryland School of Medicine, recalled her arrival at the university when it was in the midst of "unsettling change." She called Dr. Rennels "a steadying force."
"He was so wise in many ways," she said. "When things got hot, he would use his dry Western humor to defuse the situation. He would calm people down, assure them that things would get better."
Science writers and reporters struggling to understand the complexity of brain research would often seek out Dr. Rennels, said Mr. Franklin, who first met the doctor during a brain dissection.
"He was one of the best scientists I ever knew, with a childlike curiosity about nearly everything," Mr. Franklin said. "Whenever I was trying to make sense out of something, I would end up talking to Marshall."
Early in the space exploration program, Mr. Franklin finagled a press pass for his friend. The two traveled to Cape Canaveral, Fla., to witness a launch. Dr. Rennels called the trip "one of those peak experiences in life," Mr. Franklin said.
The family is planning a memorial service at a later date.
In addition to his wife, survivors include sisters Sharon Rennels of Sergeant Bluff and Carolyn Foreshoe of Kansas City, Mo.