Fig. 3.

p73 is essential for maintenance of cortical neurons during the first 2 postnatal weeks. a–c, Photomicrographs of immunostaining for the neuron-specific protein NeuN on coronal sections of the p73+/+ versus p73−/− cortex at P1–P3 (a) and P14–P16 (b).c, Higher magnification photomicrograph taken at the caudal level at P14–P16. Scale bars: a,b, 200 μm; c, 80 μm.d, e, Graphs showing the mean relative number of NeuN-positive neurons at the rostral (R), caudal (C), and lateral (L) levels in coronal sections of the p73+/+ (black bars) versus p73−/− (striped bars) brain at P1–P3 (d) and P14–P16 (e). Results are mean ± SEM. ***p < 0.005. f, Apoptosis is enhanced in p73−/− cortex during the first postnatal week. Photomicrographs of coronal sections at the caudal level of P4–P6 p73+/+ versus p73−/− brains analyzed by TUNEL (red,top two panels) and counterstained with Hoechst (blue, bottom two panels) are shown. Thetwo right panels are photographs of the same field, as are the two left panels. Inset, Graph of the total number of TUNEL-positive cells found in the cortex at the caudal level of p73+/+ (black bar), p73+/− (hatched bar), and p73−/− (striped bar) animals. Asterisks indicate significance relative to the p73−/− numbers (*p < 0.05; **p < 0.005). Scale bar, 150 μm.