Sheet plastination sections of the cavernous sinus.

<p><b>A, B</b> and <b>C</b> are the sagittal, transverse and coronal sections, respectively. <b>D, E</b> and <b>F</b> are the mirror confocal images of the selected areas (dashed-line boxes) of <b>A</b> and <b>C</b>. <b>A:</b> A sagittal section through the cavernous sinus at the level of the lateral edge of the dorsum sellae (DS). Arrows point to the dural roof of the cavernous sinus. Asterisks indicate the areas that are mainly occupied by adipose tissue and small cavernous veins (cv). <b>B:</b> A transverse section at the level of nerves V₁ and VI. Arrows point the lateral meningeal wall of the sinus. Asterisks indicate the dumbbell-shaped adipose zone medial to intracavernous cranial nerves III, IV, V₁ and VI. <b>C:</b> A coronal section at the middle level of the cavernous sinus. A cerebral bridging vein (BV) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089182#pone-0089182-g002" target="_blank">Figure 2D</a> for its anterior segment) entered the sinus between the lateral meningeal wall (arrows) and nerve V₂. <b>D:</b> The mirror confocal image of the dashed-line box in C, showing that the dural trabeculae (single arrowheads) originate from the medial laminae of the lateral dural wall (arrows) and encircle the branches of nerves V₁ and VI, forming a dural trabecular network. Some dural trabeculae (double arrowheads) spirally encircle a nerve and contribute to the sleeve of the nerve. Asterisk indicates a fine trabecular network. <b>E:</b> The mirror confocal image of an area in the dashed-line circle in A, showing that some dural trabeculae (single arrowheads) from Meckel's cave (MC) longitudinally and loosely accompany a branch of nerve V₁. <b>F:</b> The mirror confocal image of another area in the dashed-line circle in A, showing that the longitudinal dural fibers (single arrowheads) scatter and merge with the fine trabeculae in adipose tissue (asterisks). The dashed-line circles outline the basal membrane of some adipocytes. Double asterisks indicate a small vessel. ACP: anterior clinoid process; BV: cerebral bridging vein; CA: internal carotid artery; cv: cavernous veins; DS: dorsum sellae; MC: Meckel's cave; PG: pituitary gland; Sph: sphenoid bone; TL: temporal lobe; Cranial nerves II, III, IV, V₁, V₂ and VI; bars = 1 mm.</p

Localization of the adipose zone (A–C) and fibrous configuration of the sleeves of cranial nerves III and IV (D–G).

<p><b>A:</b> A transverse section through the cavernous segment of the internal carotid artery (CA). <b>B:</b> The mirror confocal image of the dashed-line box in A, showing a large anterior end of the dumbbell-shaped adipose zone (asterisks) on the surface of the sphenoid bone (Sph), anterior to the internal carotid artery (CA) and its surrounding cavernous veins (cv), and posteromedial to the anterior clinoid process (ACP). Arrows point to the lateral meningeal dural wall of the sinus. <b>C:</b> The mirror confocal image of the solid line box in A, showing a small and irregular posterior end of the dumbbell-shaped adipose zone (asterisks) medial to the sleeves of the intracavernous cranial nerves VI and V₁ and Meckel's cave (MC). Single arrowheads point to the dural trabeculae and arrows indicate multiple laminae of the lateral meningeal wall of the sinus. <b>D:</b> A coronal section at the level of the anterior clinoid process (ACP), about 6 mm anterior to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089182#pone-0089182-g001" target="_blank">Figure 1C</a>. A cerebral bridging vein (BV) is located lateral to intracavernous cranial nerves III, IV, V₁, V₂ and VI. <b>E:</b> The mirror confocal image of the dashed-line box in D, showing that the dural trabeculae (single arrowheads) originate from the meningeal dura of the anterior clinoid process (ACP), encircle nerves III and IV and connect with the fine trabecular network (asterisk) and sleeves of nerves V₁ and VI. Double arrowheads indicate the wall of the bridging vein. Single arrows point to the lateral wall of the cavernous sinus. <b>F</b> and <b>G:</b> The confocal images of two adjacent coronal sections about 6 mm (F) and 12 mm (G) posterior to E, showing that nerve III and its associated arachnoid cuff (asterisk) invaginate in the later wall (G) and then pieces the wall (F). The insert of F is from a different coronal section, showing that nerve IV pieces the lateral wall. Arrows point to the multiple laminae of the lateral dural wall of the cavernous sinus. Arrowheads point to the dural trabeculae originating from the medial lamina of the wall. ACP: anterior clinoid process; BV: cerebral bridging vein; CA: internal carotid artery; cv: cavernous veins; DS: dorsum sellae; MC: Meckel's cave; PG: pituitary gland; SAS: subarachnoid space; Sph: sphenoid bone; TL: temporal lobe; Cranial nerves III, IV, V₁, V₂ and VI; bars = 1 mm.</p

Unique subcellular distribution of phosphorylated Plk1 (Ser137 and Thr210) in mouse oocytes during meiotic division and pPlk1^Ser137 involvement in spindle formation and REC8 cleavage

<div><p>Polo-like kinase 1 (Plk1) is pivotal for proper mitotic progression, its targeting activity is regulated by precise subcellular positioning and phosphorylation. Here we assessed the protein expression, subcellular localization and possible functions of phosphorylated Plk1 (pPlk1^Ser137 and pPlk1^Thr210) in mouse oocytes during meiotic division. Western blot analysis revealed a peptide of pPlk1^Ser137 with high and stable expression from germinal vesicle (GV) until metaphase II (MII), while pPlk1^Thr210 was detected as one large single band at GV stage and 2 small bands after germinal vesicle breakdown (GVBD), which maintained stable up to MII. Immunofluorescence analysis showed pPlk1^Ser137 was colocalized with microtubule organizing center (MTOC) proteins, γ-tubulin and pericentrin, on spindle poles, concomitantly with persistent concentration at centromeres and dynamic aggregation between chromosome arms. Differently, pPlk1^Thr210 was persistently distributed across the whole body of chromosomes after meiotic resumption. The specific Plk1 inhibitor, BI2536, repressed pPlk1^Ser137 accumulation at MTOCs and between chromosome arms, consequently disturbed γ-tubulin and pericentrin recruiting to MTOCs, destroyed meiotic spindle formation, and delayed REC8 cleavage, therefore arresting oocytes at metaphase I (MI) with chromosome misalignment. BI2536 completely reversed the premature degradation of REC8 and precocious segregation of chromosomes induced with okadaic acid (OA), an inhibitor to protein phosphatase 2A. Additionally, the protein levels of pPlk1^Ser137 and pPlk1^Thr210, as well as the subcellular distribution of pPlk1^Thr210, were not affected by BI2536. Taken together, our results demonstrate that Plk1 activity is required for meiotic spindle assembly and REC8 cleavage, with pPlk1^Ser137 is the action executor, in mouse oocytes during meiotic division.</p></div