Figure 4.
A-F, Fos expression in the ventral hippocampal formation of a control mouse (A; Cont) and pilocarpine-treated mice (B-F) at different intervals after spontaneous seizures. A, In control animals, Fos immunoreactivity is detected in scattered cells in the granule cell layer (G) of the dentate gyrus, pyramidal cell layer (P) of CA3 and CA1, subiculum (S), presubiculum (PrS), parasubiculum (PaS), and entorhinal cortex (Ent). B, At 15 min after a spontaneous seizure, elevated Fos immunoreactivity is evident in the dentate granule cell layer, but the number of scattered, strongly labeled cells, evident in the control tissue, is reduced throughout many other regions of the hippocampal formation. C, At 30 min after a spontaneous seizure, Fos labeling is very strong in the dentate granule cell layer. Increased Fos labeling is also evident in most other regions of the hippocampal formation. D, At 1 h after a spontaneous seizure, Fos immunoreactivity remains high in most hippocampal regions. Distinct labeling is present in the dentate granule cell layer, although the intensity of labeling is lower than at 30 min. E, By 2 h after a seizure, Fos immunoreactivity in the granule cell layer is substantially lower than that observed after 30 min and 1 h. However, labeled cells are evident in the hilus, and some strongly labeled large cells are evident along the inner border of the granule cell layer (arrow). F, By 4 h after a spontaneous seizure, Fos labeling is low throughout the hippocampal formation, and the number of scattered Fos-labeled cells appears lower than in control animals (compare with A). Scale bar: (in F) A-F, 200 μm.