The effects of prolonged formalin fixation on immunohistochemical staining of PCNA and Dcx proteins in the mouse hippocampus

We have performed a quantitative analysis of temporal pattern of immunohistochemical staining to PCNA and Dcx in brain tissue under the influence of 10% neutral buffered formalin (fixation for 3.5 h–7 weeks). After 7 days of fixation we found a decrease in Dcx and, to a lesser extent, PCNA immunoreactivity. Later, no further decline in immunoreactivity occurred. Our data may be useful for optimization of neurogenesis assessment protocols in mammalian and human brains.