Pregnancy Promotes Maternal Hippocampal Neurogenesis in Guinea Pigs

Figure 1

Characterization of cytogenetic activity with the cell cycle marker Ki67 in time-pregnant guinea pigs at early gestational, late gestational, postpartal, and postweaning stages relative to age-matched nonpregnant females. The pregnant animals are at the end of the third (GW3) and seventh (GW7) weeks of gestation and at the end of the second (PPW2) and fourth (PPW4) weeks postpartum, respectively. Representative images of Ki67 immunolabeling (brown) with hematoxylin counterstain (blue) from individual animal groups are illustrated as indicated. The left panels (a, d, j, and m) are low-magnification images showing the orientation of Ammon’s horn (CA1, CA3) and dentate gyrus (DG), with framed areas enlarged as the middle panels, in which boxed areas are further enlarged as the right panels. Ki67 immunoreactive (+) profiles (pointed by arrows) are nuclear in nature and localized at the subgranular zone (SGZ), with some occurring in clusters (i, l, and o). (p) shows the rostrocaudal range of hippocampal sections in each brain used to quantify Ki67+ cells in the dorsal part of the DG. (q) shows the designation of a band area for counting Ki67+ cells along the granule cell layer (GCL). This band is defined to have a height that equals to the depth (blue line) of the GCL but is moved towards the hilus by a half of the GCL thickness (purple lines). (r) plots the numeric densities of Ki67+ cells, expressed as number (#) of cells per mm of GCL length, in the groups. There is a significant difference of the medians in the groups by Kruskal-Wallis test, with that between the control and late gestational groups reaching significance () by post hoc analysis. KWS: Kruskal-Wallis scientific index. Scale  μm in (a) applying to (d, g, j, and m), equal to 100 μm for (b, e, h, k, n, and q), and 25 μm for (c, f, i, l, and o).