Randee Ladden says her friends love to hear about the time she got an assignment from a manufacturer of containers used to collect bull semen. And then there’s the 30-by-40-inch painted cross-section of a penis she was hired to do by a man involved in a malpractice lawsuit. But the cocktail-party story Ladden’s probably been telling most lately is about designing the poster for The Road to Wellville, the Alan Parker movie based on T.C. Boyle’s novel about Battle Creek Sanitarium. “The script was so wacky,” Ladden says. “I mean, the first lines were all about masturbation and being a vegetarian and colonic washes.”

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Luckily for the filmmakers, they chose an artist who could stomach the squeamish stuff: Ladden, who lives in Rogers Park, has been working as a free-lance medical illustrator for about a decade. Her colorful paintings and diagrams of stomachs, pancreatic acinars, fat cells, intestines, and colons have appeared in annual reports, catalogs, and such publications as the Journal of the American Dietetic Association and the Bulletin of the American College of Surgeons. In 1987 she rendered one of the first drawings of the HIV virus for Searle.

Ladden learned about her relatively obscure field–there are only half a dozen training programs for medical illustration in the country–from a high school counselor and kept it in the back of her mind while she pursued a premed program. She switched to medical illustration at the University of Illinois at Urbana-Champaign after suffering through an organic chemistry course. Later she got a master’s degree in biomedical communication from the University of Texas Health Science Center. (Her heart-surgeon brother fulfilled the family’s desire to produce an MD.)

The complexity of illustrations depends on their intended audience. But the conceptual challenge is always there: “What do you leave out and what do you leave in and how do you show the size relationship between things that are so small, but then put it into a context that people will understand?”