Fig. 3. Isoflurane (Iso) increases neuronal differentiation in the dentate gyrus of postnatal day (P)60 but not of P7 rats. After injection of 5-bromodeoxyuridine (BrdU) 4 h before the start of a 4 h of isoflurane anesthetic, the proportion of BrdU+ cells (  A ,  red ) that expressed the early neuronal marker NeuroD (  A ,  green ) was increased by isoflurane in P60 but not in P7 rats (  B ). The microscopic image in fig. 4A (20× objective) is a 3D-reconstruction of an image stack of a coronal section from an isoflurane-treated animal acquired on a grid confocal microscope. The  filled arrows point to BrdU+/NeuroD+ double-labeled cells in the subgranular zone of the dentate gyrus of the hippocampus. The  arrowhead points to a BrdU+/ NeuroD– cell. This image shows a greater than average proportion of double-labeled cells. Data are medians ± interquartile ranges. **  P < 0.01, ***  P < 0.001, Mann–Whitney U-test.