 Producers wanted the character of Carol, played by  Julianna Margulies (qv) to switch from being a nurse to a doctor  and even filmed episodes of her starting medical school. Margulies  objected to the idea, saying that her character would be so proud of  being a nurse she would never want to change, so the idea was  dropped. Years later, the character of Abby, played by  Maura Tierney (qv) did go from being a nurse to a doctor.