Histoscope: A Web-Based Microscopy Tool for Oral Histology Education.

OBJECTIVES: Histology, the study of tissue structure under a microscope, is one of the most essential yet least engaging topics for health professional students. Understanding tissue microanatomy is crucial for students to be able to recognize cellular structures and follow disease pathogenesis. Traditional histology teaching labs rely on light microscopes and a limited array of slides, which inhibits simultaneous observation by multiple learners, and prevents in-class discussions. We have developed an interactive web-based microscopy tool called "Histoscope" for oral histology in this context. METHODS: Good quality microscope slides were selected for digital scanning. The slides were scanned with multiple layers of z-stacking, a method of taking multiple images at different focal distances. The digital images were checked for quality and were archived on Histoscope. The slides were annotated, and self-assessment questions were prepared for the website. Interactive components were programmed on the website to mimic the experience of using a real light microscope. RESULTS: This web-based tool allows users to interact with histology slides, replicating the experience of observing and manipulating a slide under a real microscope. Through this website, learners can access a broad array of digital oral histology slides and self-assessment questions. CONCLUSIONS: Incorporation of Histoscope in a course can shift traditional teacher-centered histology learning to a collaborative and student-centered learning environment. This platform can also provide students the flexibility to study histology at their own pace.

Admission Criteria as Predictors of Student Success in a Dental Hygiene Program.

The aims of this study were to assess which prerequisites the dental hygiene faculty at the University of Alberta perceived as essential to success in the dental hygiene program and to determine if students' prerequisite grades and interview scores predicted their success in the program. Academic records of students admitted between 2004 and 2013 were examined in 2016 for prerequisite course grades, interview scores, and junior, senior, and cumulative grade point average (GPA). In addition, course instructors were surveyed about which prerequisites they deemed necessary for their particular subjects. The results showed that every prerequisite course was perceived as necessary at some point in the program. However, most prerequisite course grades were weak predictors of academic performance, with a moderate correlation between cumulative prerequisite GPA and the junior GPA and final cumulative GPA. The interview was also considered necessary for some preclinical and clinical courses. There was no correlation between interview scores and students' academic performance. These findings suggest that, although the interview and prerequisite GPA requirements filtered out unsuitable candidates, they did not predict which students would be successful in the program. More refined methods need to be devised to identify which students are most likely to succeed.

Variations in structure of the outflow tract of the human embryonic heart: A new hypothesis for generating bicuspid aortic semilunar valves.

Outflow tract development of the heart is complex. The presence, differential growth and interactions of the various tissues through space and time contribute to the final development of the tract. This paper presents a novel interpretation of observations of outflow tract development, in particular of the aortic and pulmonary semilunar valves in embryos from the Shaner Collection at the University of Alberta. Three-dimensional reconstructions assist in the visualization of the spatial relationships of the developing valve tissues. In some embryos the aortic intercalated valve swelling is displaced proximally, giving rise to a bicuspid aortic semilunar valve more distally. In addition, the developing valve tissue first appears external to the myocardial cuff. The pulmonary semilunar valve regions appear to be more normal. This paper thus proposes a novel mechanism for generating a bicuspid aortic valve and also supports the idea that there is some independence of the aortic and pulmonary regions from each other during development.

The different effects on cranial and trunk neural crest cell behaviour following exposure to a low concentration of alcohol in vitro.

Embryonic neural crest cells give rise to large regions of the face and peripheral nervous system. Exposure of these cells to high alcohol concentrations leads to cell death in the craniofacial region resulting in facial defects. However, the effects of low concentrations of alcohol on neural crest cells are not clear. In this study, cranial neural crest cells from Xenopus laevis were cultured in an ethanol concentration approximately equivalent to one drink. Techniques were developed to study various aspects of neural crest cell behaviour and a number of cellular parameters were quantified. In the presence of alcohol, a significant number of cranial neural crest cells emigrated from the explant on fibronectin but the liberation of individual cells was delayed. The cells also remained close to the explant and their morphology changed. Cranial neural crest cells did not grow on Type 1 collagen. For the purposes of comparison, the behaviour of trunk neural crest cells was also studied. The presence of alcohol correlated with increased retention of single cells on fibronectin but left other parameters unchanged. The behaviour of trunk neural crest cells growing on Type 1 collagen in the presence of alcohol did not differ from controls. Low concentrations of alcohol therefore significantly affected both cranial and trunk neural crest cells, with a wider variety of effects on cells from the cranial as opposed to the trunk region. The results suggest that low concentrations of alcohol may be more detrimental to early events in organ formation than currently suspected.

Odontoblasts in odontogenic tumors.

Odontoblasts are secretory cells displaying epithelial and mesenchymal features, which exist in a monolayer at the interface between the dentin and pulp of a tooth. During embryogenesis, these cells form a dentin shell and throughout life continue to produce dentin while, also acting as sensor cells helping to mediate tooth sensitivity. In this process, odontoblasts are forced to migrate inwards, resulting in an ongoing loss of pulp volume. Correspondingly, there is also a decrease in the surface area of the dentin which supports the odontoblast cell layer. As these events transpire, odontoblasts maintain a tightly controlled monolayer relationship to each other as well as to their dentin substrate. Stability is maintained laterally by epithelial attachment structures and transversely by complex cytoplasmic extensions into the supporting dentin. As a result, it is not possible for the layer to buckle to relieve the mechanical stresses, which develop during the inward migration. A theoretical consequence of this distinctive self-generated niche is the development of long term compressive stresses within the odontoblast population. We present a mechanobiology model, which causally relates the increase in cellular compressive stresses to contact inhibition of proliferation. We link this hypothesis to the observation that there are no reports of pulpal odontoblasts showing neoplasia or acquisition of changes suggestive of a pre-neoplastic phenotype.