Marissa Villarreal, PA-C Marissa Villarreal, PA-C graduated with honors from the University of Texas Medical Branch, Galveston and the University of Texas Pan American-Edinburg Physician Assistant Program. She joins our group with an extensive background in Radiologic Technology and Diagnostic Medical Sonography. She is Board Certified by the National Commission on Certification of Physician Assistants as well as a member of the American Academy of Physician Assistants.