Apparatus and method for Immunohistochemistry, including a slide holder assembly fixture, a slide holder, a slide holder frame, and a slide holder frame assembly adapted to be placed in communication with a driving force to draw fluid through the slide holder. The slide holder may include an injection port that allows consistent fluid delivery and recovery, while minimizing the introduction of air bubbles. The slide holder may include a reservoir that allows for filling, soaking, rinsing, flushing, uniform antibody coverage of the tissue and reduces handling time, space, and errors, and one or more sample chambers. The slide orientation in the slide holder allows for visualization of label information and tissue to confirm adequate antibody coverage. A multi-port frame allows multiple assays to be carried out concurrently, and is removable from a vacuum manifold and allows for easy transport from the vacuum manifold to an incubator/refrigerator and back.