Investigation of risk factors for vaginal dehiscence and development of small bowel evisceration after robot-assisted radical cystectomy for female bladder cancer and an improved vaginal reconstruction technique to prevent its onset.

Transvaginal organ prolapse, such as small bowel evisceration, is a rare complication after radical cystectomy (RC) in female patients with invasive bladder cancer, However, it often requires emergency surgical repair. Here, we describe our experience with such a case and a review of similar previously reported cases, along with evaluation of the risk factors. We also propose a vaginal reconstruction technique to prevent this complication during robot-assisted laparoscopic radical cystectomy (RARC). A total of 178 patients who underwent laparoscopic radical cystectomy (LRC) or RARC were enrolled, 34 of whom (19%) were female. One of the 34 female patients had transvaginal small bowel evisceration after RARC. We evaluated our case and six such previously reported cases, to determine vaginal reconstruction techniques during RARC to prevent this complication postoperatively. Median age of these cases was 73 (51-80) years, and all patients were postmenopausal. The median time to small bowel evisceration was 14 (6-120) weeks postoperatively. In addition, we changed the methods of the vaginal reconstruction technique during RARC from the conventional side-to-side closure technique to the improved caudal-to-cephalad closure technique. Since implementing this change, we have not experienced any cases of vaginal vault dehiscence or organ prolapse. Transvaginal small bowel evisceration after RC can easily become severe. Therefore, all possible preventive measures should be taken during RARC. We believe that our vaginal reconstruction techniques might reduce the risk of developing this complication.

Surgical training in extraperitoneal laparoscopic para­aortic lymphadenectomy for the treatment of gynecological cancer using a Thiel­embalmed cadaver.

The extraperitoneal laparoscopic approach (ELPAN) for para-aortic lymphadenectomy provides excellent visibility of the left side of the aorta, thus facilitating surgery in the retroperitoneal space. This technique is highly complex compared with the transperitoneal approach. In particular, advanced techniques are required to develop an appropriate surgical field in the narrow retroperitoneal space; therefore, surgeons need to undergo a significant amount of training to become competent. A variety of tools are available for surgical training but are limited by their ability to reproduce complex anatomy. Thus, cadavers may represent the most suitable tool for learning this unique technique. The present study describes a surgical training protocol for the ELPAN technique using a Thiel-embalmed human cadaver and provides a step-by-step description of the ELPAN technique performed at Okayama University (Okayama, Japan). A 72-year-old Thiel-embalmed female cadaver was used to develop a protocol for surgical training in the ELPAN technique that effectively reproduced the methodology required in clinical practice. A training method for ELPAN surgery was developed and successfully completed using the Thiel-embalmed cadaver that secured the surgical field in the retroperitoneal space and permitted resection of the lymph nodes. The Thiel-embalmed cadaver tissue possessed excellent properties for surgical training, including color tone, flexibility, and the membrane structure of connective and fat tissues. In addition, this method of fixation preserved stiffness and elasticity of the peritoneum, although large vessels were slightly fragile and poorly extensible. Surgical training using a Thiel-embalmed human cadaver represents a valuable option for learning the ELPAN surgical technique. However, this technique may be unsuitable for training in perivenous manipulation. To the best of our knowledge, this is the first report to describe the use of Thiel-embalmed cadavers as a tool for surgeons to undergo training in the ELPAN technique.

CD206+ macrophages transventricularly infiltrate the early embryonic cerebral wall to differentiate into microglia.

The relationships between tissue-resident microglia and early macrophages, especially their lineage segregation outside the yolk sac, have been recently explored, providing a model in which a conversion from macrophages seeds microglia during brain development. However, spatiotemporal evidence to support such microglial seeding in situ and to explain how it occurs has not been obtained. By cell tracking via slice culture, intravital imaging, and Flash tag-mediated or genetic labeling, we find that intraventricular CD206+ macrophages, which are abundantly observed along the inner surface of the mouse cerebral wall, frequently enter the pallium at embryonic day 12. Immunofluorescence of the tracked cells show that postinfiltrative macrophages in the pallium acquire microglial properties while losing the CD206+ macrophage phenotype. We also find that intraventricular macrophages are supplied transepithelially from the roof plate. This study demonstrates that the "roof plate→ventricle→pallium" route is an essential path for microglial colonization into the embryonic mouse brain.

Transient microglial absence assists postmigratory cortical neurons in proper differentiation.

In the developing cortex, postmigratory neurons accumulate in the cortical plate (CP) to properly differentiate consolidating subtype identities. Microglia, despite their extensive surveying activity, temporarily disappear from the midembryonic CP. However, the mechanism and significance of this absence are unknown. Here, we show that microglia bidirectionally migrate via attraction by CXCL12 released from the meninges and subventricular zone and thereby exit the midembryonic CP. Upon nonphysiological excessive exposure to microglia in vivo or in vitro, young postmigratory and in vitro-grown CP neurons showed abnormal differentiation with disturbed expression of the subtype-associated transcription factors and genes implicated in functional neuronal maturation. Notably, this effect is primarily attributed to interleukin 6 and type I interferon secreted by microglia. These results suggest that "sanctuarization" from microglia in the midembryonic CP is required for neurons to appropriately fine-tune the expression of molecules needed for proper differentiation, thus securing the establishment of functional cortical circuit.

Cell-cycle-independent transitions in temporal identity of mammalian neural progenitor cells.

During cerebral development, many types of neurons are sequentially generated by self-renewing progenitor cells called apical progenitors (APs). Temporal changes in AP identity are thought to be responsible for neuronal diversity; however, the mechanisms underlying such changes remain largely unknown. Here we perform single-cell transcriptome analysis of individual progenitors at different developmental stages, and identify a subset of genes whose expression changes over time but is independent of differentiation status. Surprisingly, the pattern of changes in the expression of such temporal-axis genes in APs is unaffected by cell-cycle arrest. Consistent with this, transient cell-cycle arrest of APs in vivo does not prevent descendant neurons from acquiring their correct laminar fates. Analysis of cultured APs reveals that transitions in AP gene expression are driven by both cell-intrinsic and -extrinsic mechanisms. These results suggest that the timing mechanisms controlling AP temporal identity function independently of cell-cycle progression and Notch activation mode.

Migration, early axonogenesis, and Reelin-dependent layer-forming behavior of early/posterior-born Purkinje cells in the developing mouse lateral cerebellum.

BACKGROUND: Cerebellar corticogenesis begins with the assembly of Purkinje cells into the Purkinje plate (PP) by embryonic day 14.5 (E14.5) in mice. Although the dependence of PP formation on the secreted protein Reelin is well known and a prevailing model suggests that Purkinje cells migrate along the 'radial glial' fibers connecting the ventricular and pial surfaces, it is not clear how Purkinje cells behave in response to Reelin to initiate the PP. Furthermore, it is not known what nascent Purkinje cells look like in vivo. When and how Purkinje cells start axonogenesis must also be elucidated. RESULTS: We show that Purkinje cells generated on E10.5 in the posterior periventricular region of the lateral cerebellum migrate tangentially, after only transiently migrating radially, towards the anterior, exhibiting an elongated morphology consistent with axonogenesis at E12.5. After their somata reach the outer/dorsal region by E13.5, they change 'posture' by E14.5 through remodeling of non-axon (dendrite-like) processes and a switchback-like mode of somal movement towards a superficial Reelin-rich zone, while their axon-like fibers remain relatively deep, which demarcates the somata-packed portion as a plate. In reeler cerebella, the early born posterior lateral Purkinje cells are initially normal during migration with anteriorly extended axon-like fibers until E13.5, but then fail to form the PP due to lack of the posture-change step. CONCLUSIONS: Previously unknown behaviors are revealed for a subset of Purkinje cells born early in the posteior lateral cerebellum: tangential migration; early axonogenesis; and Reelin-dependent reorientation initiating PP formation. This study provides a solid basis for further elucidation of Reelin's function and the mechanisms underlying the cerebellar corticogenesis, and will contribute to the understanding of how polarization of individual cells drives overall brain morphogenesis.

Asymmetric production of surface-dividing and non-surface-dividing cortical progenitor cells.

Mature neocortical layers all derive from the cortical plate (CP), a transient zone in the dorsal telencephalon into which young neurons are continuously delivered. To understand cytogenetic and histogenetic events that trigger the emergence of the CP, we have used a slice culture technique. Most divisions at the ventricular surface generated paired cycling daughters (P/P divisions) and the majority of the P/P divisions were asymmetric in daughter cell behavior; they frequently sent one daughter cell to a non-surface (NS) position, the subventricular zone (SVZ), within a single cell-cycle length while keeping the other mitotic daughter for division at the surface. The NS-dividing cells were mostly Hu+ and their daughters were also Hu+, suggesting their commitment to the neuronal lineage and supply of early neurons at a position much closer to their destiny than from the ventricular surface. The release of a cycling daughter cell to SVZ was achieved by collapse of the ventricular process of the cell, followed by its NS division. Neurogenin2 (Ngn2) was immunohistochemically detected in a certain cycling population during G1 phase and was further restricted during G2-M phases to the SVZ-directed population. Its retroviral introduction converted surface divisions to NS divisions. The asymmetric P/P division may therefore contribute to efficient neuron/progenitor segregation required for CP initiation through cell cycle-dependent and lineage-restricted expression of Ngn2.