The Effect of Delay in Fixation, Different Fixatives, and Duration of Fixation in Estrogen and Progesterone Receptor Results in Breast Carcinoma

Immunohistochemical analysis for estrogen receptor (ER) and progesterone receptor (PR) after varying fixation times in 10% neutral buffered formalin. A, ER fixed for 1 hour (×100). B, PR fixed for 1 hour (×100). C, ER fixed for 72 hours (×100). D, PR fixed for 72 hours (×100). E, ER fixed for 168 hours (1 week; ×100). F, PR fixed for 168 hours (1 week; ×100).