Global pattern of interkinetic nuclear migration in tracheoesophageal epithelia of the mouse embryo: Interorgan and intraorgan regional differences.

Interkinetic nuclear migration (INM) is an apicobasal (AB) polarity-based regulatory mechanism of proliferation/differentiation in epithelial stem/progenitor cells. We previously documented INM in the endoderm-derived tracheal/esophageal epithelia at embryonic day (E) 11.5 and suggested that INM is involved in the development of both organs. We here investigated interorgan (trachea vs esophagus) and intraorgan regional (ventral vs dorsal) differences in the INM mode in the tracheal and esophageal epithelia of the mouse embryo. We also analyzed convergent extension (CE) and planar cell movement (PCM) in the epithelia based on cell distribution. The pregnant C57BL/6J mice were intraperitoneally injected with 5-ethynyl-2'-deoxyuridine at E11.5 and E12.5 and were sacrificed 1, 4, 6, 8, and 12 hours later to obtain the embryos. The distribution of labeled cell nuclei along the AB axis was chronologically analyzed in the total, ventral, and dorsal sides of the epithelia. The percentage distribution of the nuclei population was represented by histogram and the chronological change was analyzed statistically using multidimensional scaling. The interorgan comparison of the INM mode during E11.5-E12.0, but not E12.5-E13.0, showed a significant difference. During E11.5-E12.0 the trachea, but not the esophagus, showed a significant difference between ventral and dorsal sides. During E12.5-E13.0 neither organ showed regional differences. CE appeared to occur in both organs during E11.5-E12.0 while PCM was unclear in both organs. These findings suggest a difference between the trachea and esophagus, and a regional difference in the trachea, not in the esophagus, in the INM mode, which may be related with the later differential organogenesis/histogenesis of these organs.

Morphologic changes in the cytoskeleton and adhesion apparatus during the conversion from pseudostratified single columnar to stratified squamous epithelium in the developing mouse esophagus.

The apico-basal (AB) polarity of epithelial cells is maintained by organized arrays of the cytoskeleton and adhesion apparatus. We previously reported that mouse embryonic esophageal epithelium exhibits interkinetic nuclear migration (INM), an AB-polarity-based regulatory mechanism of stem-cell proliferation, and suggested that the pseudostratified single columnar epithelium, a hallmark of INM, is converted to stratified squamous epithelium via rearrangement of the cytoskeleton and cell-adhesion apparatus. Here, we chronologically examined morphological changes in the cytoskeleton and adhesion apparatus in the mouse esophageal epithelium at embryonic day (E) 11.5, E13.5, E14.5, and E15.5, during which epithelial conversion has been suggested to occur. We used phalloidin to examine the apical terminal web (ATW), immunofluorescent anti-zonula occludens protein (ZO-1) antibody to reveal ZO-1, and anti-gamma tubulin antibody to detect primary cilia (PC). At E11.5, a thick ATW, apically oriented ZO-1 and apical PC were observed, indicating a pseudostratified single columnar structure. At E13.5 and E14.5, the phalloidin-staining, ZO-1, and PC distribution patterns were not apically localized, and the epithelial cells appeared to have lost the AB polarity, suggesting conversion of the epithelial structure and cessation of INM. At E15.5, light and transmission electron microscope observations revealed the ATW, ZO-1, PC, and tight junction which were localized into two-1ayers: the apical and subapical layers of the epithelium. These findings suggest that dynamic remodeling of the cytoskeleton and adhesion apparatus is involved in the conversion from pseudostratified single columnar to stratified squamous morphology and is closely related with temporal perturbation of the AB-polarity and cessation of INM.

Interkinetic nuclear migration in the tracheal and esophageal epithelia of the mouse embryo: Possible implications for tracheo-esophageal anomalies.

Interkinetic nuclear migration (INM) is a cell polarity-based phenomenon in which progenitor cell nuclei migrate along the apico-basal axis of the pseudostratified epithelium in synchrony with the cell cycle. INM is suggested to be at least partially cytoskeleton-dependent and to regulate not only the proliferation/differentiation of stem/progenitor cells but also the localized/overall size and shape of organs/tissues. INM occurs in all three of the germ-layer derived epithelia, including the endoderm-derived gut. However, INM has not been documented in the esophagus and respiratory tube arising from the anterior foregut. Esophageal atresia with or without trachea-esophageal fistula (EA/TEF) is a relatively common developmental defect. Transcription factors and signaling molecules have been implicated in EA/TEF, but the etiology of EA/TEF-which has been suggested to involve cell polarity-related mechanisms-remains highly controversial. In the present study, we first examined whether INM exists in the trachea and esophagus of mouse embryos at embryonic day 11.5 (E11.5), just after separation of the two tubes from the anterior foregut. By labeling the DNA-synthesizing stem cell nuclei with 5-ethynyl-2'-deoxyuridine, a nucleotide analogue, and statistically analyzing chronological changes in the distribution pattern of the labeled nuclei by using multidimensional scaling, we showed the existence of INM in both the esophagus and trachea, with differences in the INM magnitude and cycle pattern. We further showed morphological changes from the INM-based pseudostratified single layer to the stratified multilayer in the esophageal epithelium in association with a temporal loss/perturbation of AB polarity, suggesting a possible relation with the pathogenesis of EA/TEF.

The Clinical Significance of Ulnar Artery Morphology in Artificial Arterial-Venous Fistula for Hemodialysis.

BACKGROUND: The ulnar artery is a terminal branch of the brachial artery. The aim of this study is to provide comprehensive data concerning the morphology of the ulnar artery, with clinical implications for surgeons. METHODS: The current study includes the dissection of 68 upper limb specimens. It investigates the characteristics of the ulnar artery such as the internal diameter, external diameter, wall thickness, and distance of the ulnar artery origin. RESULTS: In this study, the ulnar artery arose distal to the superior margin of the head of the radius in 82.65% of cases. The angle degree of the ulnar artery with respect to the brachial artery ranges from to 8° to 30°. The internal and external diameters of the ulnar artery were found to decrease gradually from proximal to distal in both genders. The external and internal diameters of the ulnar artery are greater in males than in females. In all cases, the external and internal diameters and the thickness of the ulnar artery at three levels were found to be greater in the right ulnar artery than the left. CONCLUSION: The right ulnar artery may be the appropriate choice for artificial arterial-venous fistula for haemodialysis. Due to its wide diameter, the proximal part of the radial artery is a suitable site for the artificial arterial-venous fistula immediately below the origin prior to its profound course. Therefore, it is an easy access for artificial arterial-venous fistula for surgeons. The radiologists must alert the surgeons for surgical modification in the case of high brachial bifurcation.

Reaction of medical students to experiences in dissection room.

BACKGROUND: As preclinical medical students start and/or enter the course, they go through the anatomy curriculum, which involves interaction with cadavers and cadaveric material. The objective of this study was to determine the reactions of preclinical medical students from year two and year three to the dissecting room. METHODS: Questionnaire was distributed to all second and third year medical students. The questionnaire was designed with the objective of identifying specific patterns of attitudes held and problems faced by the students in their first exposure to the human cadaver. The results are analyzed statistically using the SPSS 16.0 software and P< 0.05 was considered statistically significant. RESULTS: The commonest symptoms experienced were loss of appetite (43.29% year 2 and 34.86 % third year students). The commonest cause of their symptoms was studied and the result shows that it was the smell of the dissection room, as reported by 67.01% of year two students; and 54.12% for year 3 students. CONCLUSION: The present study findings show that smell of the dissection room, touch and fear of cadaver were the commonest cause of their symptoms experienced while study in dissection room for the majority of students. Thus, instructors are should give awareness raising education before the commencement of the dissection session to the students both mentally and emotionally ready to do their work enthusiastically and confidently. Moreover, it is necessary to make the laboratory tidy for the students so that they develop a love for the dissection room.