Distribution and quantification of phosphorylated MAPK (p-MAPK) in rat oocytes.

<p>Oocytes collected 19 h post hCG were aged for different times in mR1ECM before examination for p-MAPK expression. A. Laser confocal micrographs showing p-MAPK distribution. Whereas images in different rows show a non-SA oocyte remaining at the MII stage (nSA), a SA oocyte observed at 1 h (SA1h) and a SA oocyte observed at 6 h (SA6h) of in vitro aging, respectively, images in different columns show α-tubulin, p-MAPK, chromatin and merged pictures, respectively. The scale bar is 20 µm. B is a graph showing p-MAPK quantification in SA and non-SA (NSA) oocytes aged in vitro for 0, 1 and 6 h. Each treatment was repeated 3 times and each replicate contained 6–8 oocytes. Values without a common letter above their bars differ (p<0.05).</p

Pronuclear formation after rat oocytes were injected with BUB1 or MAD2 antibodies.

<p>Rat oocytes collected 19 h post hCG were aged in mR1ECM for 5 h before antibody injection and after the injection, the oocytes were cultured for 6 h for pronuclear formation. Each treatment was repeated 3 times with about 25–35 oocytes in each replicate.</p>a–c<p>: Values with different letter in superscripts differ significantly (P<0.05) within a column.</p

Confocal images of rat oocytes at different stages of IA (left column) or SA (right column).

<p>The DNA and α-tubulin in oocytes were pseudo-colored blue and green, respectively. A is an oocyte at the metaphase II (MII) stage showing a regular spindle with chromosomes aligned on the metaphase plate. B is an IA oocyte in anaphase II (AnII) showing a spindle with chromosomes tidily aligned on either pole. C is an IA oocyte in early telophase II (e-TelII) with a condensed chromosome mass on either pole of the spindle and the initiation of PB2 extrusion. D is an IA oocyte in late telophase II (l-TelII) with extruded PB2 and the initiation of chromosome decondensation. E is an IA oocyte in interphase (Int) with pronuclear formation. F is a SA oocyte in AnII with chromosomes dispersed over the surface of the spindle. G is a SA oocyte in e-TelII with chromosomes arranged toward the spindle poles. H and I are SA oocytes in l-TelII showing disintegrated spindles with chromosomes surrounded by microtubules scattered in the ooplasm. J is a SA oocyte at the MIII stage with microtubules reorganized into several small spindles around the scattered chromosomes. PB2 (arrow) was often observed in IA oocytes but not in SA oocytes. Scale bar is 20 µm.</p

Ca²⁺ oscillations during IA or SA of rat oocytes.

<p>Ca²⁺ oscillations during IA or SA of rat oocytes.</p

Possible pathways leading to the MIII arrest in SA oocytes and the pronuclear formation in IA oocytes.

<p>For a detailed explanation, please refer to the text in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032044#s3" target="_blank">Discussion</a> section. Because APC activity was not actually examined in this study, dotted lines were used to depict the possible pathways involving the APC activity in this figure.</p

A diagram depicting the overall hypothesis of the study.

<p>Refer to the last paragraph of the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032044#s1" target="_blank">Introduction</a> section for detailed explanations.</p

Percentages of oocytes at different stages of SA at different times during culture in mR1ECM of rat oocytes collected 19 h post hCG injection.

a–d<p>: Values with a common letter in their superscripts do not differ (P>0.05) in the same column. Each treatment was repeated 3–4 times with 15–20 oocytes in each replicate.</p

Changes in MPF and MAPK activities of rat oocytes during SA of in vitro culture or during IA after Sr²⁺ treatment.

<p>Oocytes for SA were collected 19 h post hCG and cultured for different times in mR1ECM medium before kinase assay. For IA, newly ovulated oocytes collected 13 h post hCG injection were treated with SrCl₂ for 15 min and were assayed for kinase activities at different times after SrCl₂ treatment. a-g: Values without a common letter differ (P<0.05).</p

Effect of different media on CG distribution in porcine oocytes after preservation.

<p>A. a, b, CGs perinuclear area distribution within the porcine oocytes; a, most of the CGs aggregate in the perinuclear area, with a few migrating to the central inner cytoplasm or cortical area; b is intermediate pattern between a and c, with most of the CGs still remaining in perinuclear area and some migrating to the central cytoplasm; c, CGs distributed uniformly in the inner cytoplasmic area, and a few migrated to the cortical area to form a discontinuous ring; d, CGs cortical area distribution; almost all of the CGs have migrated into the cortical area, and a few still remained in the central cytoplasm. Green, cortical granules. Scale bar = 10 µm. (White arrows pointing at the white circle denotes the germinal vesicle). B. Ratios of different CG distribution patterns within the porcine oocytes after preservation in different media. Porcine oocytes were preserved in TCM-199, pFF and FCS at 27.5°C for 3 d, and then CG distribution was stained with FITC-labeled peanut agglutinin. Three categories of CG distribution were detected: perinuclear area; inner cyoplasmic area; cortical area. The graph shows the mean ± SEM of three independent experiments. The number “n” in the bracket means the total treated oocyte in every group. The superscripts ^{a, b} over the bars represent values that differ significantly in every categories of CG distribution (P<0.05).</p

Effects of different preservation media on GSH level after preservation at 27.5°C for 3 d.

<p>Data are presented as means ± SEM from three replicated experiments.</p>a, b, c<p>Values with different superscripts are significantly different in each column (P<0.05).</p