From Microscopes to Virtual Reality – How Our Teaching of Histology is Changing

Abstract

For a long time, histology has been a well-established, fundamental part of many biomedical curricula. As it provides a bridge from the macroscopic field of gross anatomy to the molecular sciences such as biochemistry, physiology and pharmacology, histology constitutes a central link between the visible and the submicroscopic dimension. In addition, by contrasting normal tissue structures and functions with changes seen under disease conditions it serves as a gateway to pathology. Histology as a scientific field and as an educational subject has always relied on technology, initially the introductions of reliable, high-quality light microscopes about 150 years ago. This enabled students and researchers to analyze tissues and cell structures at an increasingly smaller scale. The microscopic dimension and its reliance on visual information for the interpretation and understanding of tissue structure and function still provide major challenges for many students, who study histology for the first time. Over the last decade new technological advances have resulted in significant changes how we teach histology to our students [1-3]. One of which is the abandonment of traditional light microscopes in favor of digital histological images, referred to as " virtual microscopy " [4-9]. In this overview, I would like to use the experiences, which we made using virtual microscopy for teaching histology at the University of Michigan, to discuss the advantages and disadvantages, as well as future possibilities these new technologies provide to us for teaching a traditional subject to today's computer-savvy generation of students and how these students make increasing use of virtual microscopy and other electronic resources. So why is the use of real light microscopes no longer " cool " for teaching histology? For many years, students have been studying sets of histological glass slides by regular light microscopy. However, the maintenance of a large number of student microscopes for teaching purposes and of sizeable collections of glass slides makes this approach a constant financial drain on any educational institution. As the quality of histological preparations is inherently variable and as glass, slides of many tissues, especially of human origin, are difficult or impossible to come by or to replace, this often results in great disparities between the learning resources that are available to individual students. On the positive side, students are required to learn the intricacies of manipulating a light microscope and to appreciate the variability of the biological material they have at their disposal. Over the last decade, more and more institutions of higher learning offer histology and pathology courses that partially or entirely rely on virtual microscopy as a main teaching tool [3]. Regular histological glass slides, which can be selected for quality of tissue preservation and histological staining, are scanned and converted into high-resolution digital images that are stored electronically on fast, high capacity computer servers. Students can access these images through local networks or the Internet and view them using regular computer monitors. As an example, the University of Michigan virtual histology slide collection is freely accessible through the Internet at http://histology.med.umich.edu. Appropriate software allows each student to select specific regions of interest on the slide, to zoom in and out and to move to other areas at their free choice. Like using Google Earth, only a small portion of the often Gb-size virtual image file is downloaded at a given time. This provides students with a viewing experience that is very comparable to real histological glass slides (Figure 1). In addition, every student in each class has equivalent access to the highest quality slide material. However, as a drawback, virtual microscopy delivers only a single plane of focus, thus lacking the vestige of three-dimensionality, which students can obtain using the fine focus knob of a regular microscope. In addition, virtual microscopy