Diagrams.

<p>(<i>Upper panel</i>): Flow diagram of Exp. #1 regarding times and type of treatment with pentylenetetrazole. <i>(Lower panel):</i> Schematic diagram of the distribution of proliferative (BrdU-positive) cells in the brain at day 25 after a single administration of a convulsive dose of PTZ. Note the change from a widespread distribution (<b>A</b>) to a more restricted distribution at 25 days post-seizure (<b>B</b>). In control rats, there were only a few BrdU-positive cells, often in a duplex, mitosis-like state (<b>C, D, E</b>). Many proliferative cells in PTZ-treated animals appeared to enter the brain from the circulation via leptomeningeal blood vessels (<b>F</b>, arrow points to a mitosis-like state). (<b>G</b>, <b>H</b>): Quantitation of BrdU-positive cells. One episode of convulsive seizure causes, at day 3, dramatically increased BrdU-positive cell numbers in the hippocampus (15-fold over controls; p = 0.001) (<b>G</b>) and temporal neocortex (22.5-fold over controls; p = 0.001) (<b>H</b>). Although the numbers of BrdU-positive cells decreased dramatically by day 25, their number remained, nonetheless, at relatively high levels in the hippocampus (4.8-fold; p = 0.001)(<b>G</b>) and temporal neocortex (5.6-fold; p = 0.001) (<b>H</b>) over control levels. N = 15 rats for each timepoint. <i>Abbreviations</i>: <i>Te-II</i>, temporal neocortex layer II; <i>Ent</i>, entorhinal neocortex; <i>HC</i>, hippocampus; <i>lep</i>, leptomeninx. Bars: (<b>C, D, E</b>), 20 µm; (<b>F</b>), 30 µm.