A Digital Approach to Cellular Ultrastructure in Medical Histology: Creation and Implementation of an Interactive Atlas of Electron Microscopy

INTRODUCTION

At the University of Kentucky, the medical histology course is an interdisciplinary, team-taught course that integrates the basic science of cell biology and histology with its clinical relevance (neuroscience, hematology, endocrinology, urology). Medical histology is taught in the first block of coursework, from August through October. Four faculty members provide lecture instruction and laboratory assistance to 95 first year medical students during each laboratory period.

Traditionally, histology students at the University of Kentucky studied cellular ultrastructure in the laboratory using a labeled set of electron micrographs, organized into three notebooks by topic. An accompanying set of unlabeled micrographs was available for self-testing purposes. Student use of the images in these notebooks was restricted to the histology laboratory; they had no comprehensive atlas or reference guide to facilitate their study at home or in the medical library, thereby limiting their flexibility in studying cellular ultrastructure.

This instructional dilemma presented an ideal opportunity for incorporating computer-assisted instruction (CAI) into the course by converting the micrographs in the notebooks into an accessible, interactive multimedia program. The use of CAI has become commonplace in both the basic science 1-3 and clinical aspects of medical education.^4-7 As curricular demands increase and contact hours are reduced, CAI plays an increasingly important role in the delivery of instructional materials earmarked for independent study. CAI has proven to be particularly useful in facilitating independent study in anatomical instruction, since it provides an effective and efficient way to learn visual material.^8-10 In fact, at the University of Kentucky, instructional multimedia serves as an integral component of medical gross anatomy to facilitate independent study of cross sectional anatomy, radiology and osteology. During their third block of coursework, our students use a customized digital neuroscience atlas to guide their study of neuroanatomy.¹¹

A number of medical schools have demonstrated that CAI is a viable addition to, if not a replacement for, glass slides and microscopes in medical histology.^{8, 9, 12-15} Although the study of cellular ultrastructure by electron microscopy (EM) is an integral part of many medical histology courses, this topic is sparsely covered in most commercial histology atlases, which instead emphasize light micrographs. This study reports on the development and implementation of a digital atlas of electron microscopy and the resultant student perceptions and attitudes towards the value of CAI as a tool for independent study of cellular ultrastructure.

MATERIALS AND METHODS

The Atlas
In order to facilitate student independent study of cellular ultrastructure, a customized digital atlas was constructed during the summer of 2001 using the multimedia-authoring program Macromedia Authorware 5. Unlabeled electron micrographs from the course set of notebooks were digitized using a flat bed scanner at a resolution of 1200 dpi. The images were digitally enhanced using Adobe Photoshop and imported into Macromedia Authorware 5. This program provides an icon-based template for creating sophisticated instructional multimedia with a minimal amount of programming skills.

The atlas consists of 12 self-study units, including cytology, epithelia, connective tissue, muscle, nerve, blood and circulatory system, as well as digestive, endocrine, respiratory, reproductive and urinary systems. Each screen displays an electron micrograph and an interactive list of key terms for identification. As students move their cursor over each term listed, the term and the corresponding structure on the image are highlighted (Figure 1A). Additionally, as a student passes the cursor over structures on the EM, the appropriate term is highlighted (Figure 1B). A ‘search’ feature enables students to locate a specific structure quickly, without navigating aimlessly through each module. An in-class demonstration of the atlas’ functionality was given during the first week of class and the program was distributed to all students on CD.
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Student surveys and statistical analysis
The impact of incorporating the atlas into the medical histology course was assessed using pre- and post-use surveys (Table 1). Both surveys included ten questions regarding students’ demographic information (including parameters such as age, gender, undergraduate major), as well as queries regarding students’ attitudes toward CAI, recorded on a five-point Likert-type scale (strongly agree, agree, no opinion, disagree, strongly disagree). In addition, each survey provided space for students’ subjective comments.

The pre-use survey was administered during the first week of medical histology in order to understand students’ experiences with instructional technology during their undergraduate experience. During the last week of the course, the post-use survey measured student usage patterns and satisfaction level with specific aspects of the digital EM atlas. Data collected from the post-use survey included frequency and location of use of the EM atlas, as well as its impact on learning efficiency, exam performance and ‘out of class’ study time, as perceived by the students.

Statistical analyses were performed using chi-square tests to detect significant differences in frequency data. The proportion of students responding in each of the five categories (strongly agree to strongly disagree) was calculated from the pre-use survey and this proportion was multiplied by the total number of respondents for each question in post use survey to calculate expected values. An exemption certification for this study (Protocol 01-0689-X3Q) was granted from the University of Kentucky’s Institutional Review Board.

RESULTS

Atlas Usage Patterns
The overall response rate for pre- and post-use questionnaires (2001) was 98% (n = 93 respondents out of a total of 95 students). Fifty -six (60%) of the respondents were male students and 37 (40%) were female.

When queried about their comfort level with CAI (based on their undergraduate or pre-medical experience) in the pre-use survey, 37% of the class reported feeling very comfortable using CAI, while 54% were comfortable and 9% expressed a significant level of discomfort using computer-based instructional technology. Regarding location of atlas use, most students (88%) reported using it primarily for study at home rather than in the laboratory, library or student computer lab. By contrast, the pre-use survey revealed that only 31% of these students reported using computer-assisted learning tools at home prior to medical school.

Both pre- and post-use survey data indicated students’ preference for using CAI for independent study as compared to group study (Figure 2). A significant increase in students using CAI for independent study was observed between pre- and post-use survey data (Table 2). Additionally, fewer students reported using the atlas in groups as compared to their use of prior CAI (Figure 2).

When comparing CAI usage patterns in students’ undergraduate experiences with atlas usage patterns in medical school, a number of differences were observed. The overall frequency of CAI use was elevated in medical school, as compared to CAI use in the undergraduate experience (Figure 3). Prior to medical school, 29% of students reported using CAI routinely, while only 6% of students used the digital atlas on a routine, weekly basis. Instead, most students (83%) used the digital atlas primarily as a review prior to examinations.

Students were significantly more enthusiastic (more students strongly agreed) that their study efficiency was increased after using the atlas as compared with CAI they used in their other first- year medical courses (Figure 4; Table 2). More students strongly agreed that performance was increased after using the atlas than with other CAI they had used (Figure 5; Table 2). While most students expressed that use of the atlas reduced their study time in the laboratory (38% strongly agreed; 47% agreed; 10% disagreed; 5% strongly disagreed), they were less enthusiastic about the atlas’ effect on this aspect of their study behavior.

Forty-two percent of the class reported taking histology as undergraduate students in the pre- and post-use surveys. Students’ prior histology experience or lack thereof had no significant effect on their attitudes toward or use of the atlas; there were no significant differences in attitudes towards CAI or atlas usage patterns between these two subgroups of the class.

DISCUSSION

The present study evaluated student acceptance of a computer-based atlas of electron microscopy introduced into the medical histology course at the University of Kentucky in 2001. Traditionally, students mastered cellular ultrastructure by independent study of labeled electron micrographs (EMs) in a series of large notebooks restricted to use in the laboratory. Since these EMs were not available for checkout from the lab and most medical histology atlases lack a substantial ultrastructural component, students had no resources available to them for off-site study.

As expected, the introduction of the digital EM atlas evoked an overwhelmingly positive student response. The majority of the class reported that the atlas not only made their study more efficient and convenient, but felt it enhanced their performance on lab practical exams as well. Students’ subjective comments indicated that using the atlas took ‘the guesswork’ out of mastering the sub-cellular anatomy of the electron micrographs, as many of the micrographs in the lab notebooks were unlabeled. Student satisfaction levels with the EM atlas were significantly higher than those reported for CAI used in the undergraduate experience, probably because the EM atlas was constructed ‘in-house,’ with specific course objectives in mind. The atlas was designed to provide a portable and convenient means by which to study cellular ultrastructure. For a quick review of important structures, students simply put their cursor over individual terms in the identification list to highlight each structure on the micrograph. For a more thorough review, students had the option of ‘exploring’ each micrograph with their mouse; as they passed over a structure on the EM, the appropriate term in the identification list became highlighted.

Despite the students’ strong support for the program, as measured by the post-use survey, they primarily used the atlas for review one to two days prior to examinations, rather than as a routine component of their study regime. This pattern of EM study parallels that observed prior to introduction of the digital atlas. The daily laboratory exercises emphasized identification using light microscopy, with EM structures listed at the end of each lab session, at a time when many students were rushing to complete their microscope work for the day. As a result, many students left the EM work for ‘last minute’ study just prior to the lab practical exam. McNulty and colleagues 16 have reported that even digital histology programs focusing on light microscopic images may be accessed ‘occasionally,’ rather than weekly or daily, by more than one- third of the class. Increased use of CAI prior to examinations is a common student behavior at all academic levels, however, and has been documented in electronic tracking studies of medical students using web-based CAI.¹⁶

Efforts are currently underway to encourage students to incorporate the digital EM atlas into their routine study schedule. Modifications in the design of the atlas and lab manual may promote more consistent student use of the atlas. Construction of an interactive quiz module has been initiated in order to promote periodic self- evaluation. In the current form of the course’s lab manual, a list of key EM structures is included at the end of each lab exercise in the course lab guide, so it is easy for students to overlook the EM work as they rush to finish their microscope work in the lab. By better integrating the EM work into each lab exercise in the lab manual, the students will view this aspect of the lab as an important facet of the lab experience, rather than an afterthought.

Students’ subjective comments about the program indicate that cross- referencing the EM work in the lab manual and the EM atlas would facilitate their study of the material. Including EM structures on quizzes in addition to midterm and final exams may also encourage more consistent use of the program throughout the block. Incorporation of EM images into the daily lab previews might also serve as an added incentive.

CONCLUSIONS

This study describes a novel, customizable approach to teaching and learning cellular ultrastructure in medical histology. Students’ attitudes about and use of the digital EM atlas differed significantly from computer-assisted instructional (CAI) programs they used in their pre-medical coursework. Students perceived the atlas to be more effective in increasing study efficiency and exam performance. A significantly higher proportion of students used the atlas solely for independent study than they did for pre-medical CAI. Atlas modifications are currently underway to encourage students to use the program for routine study, rather than solely for review purposes prior to exams.

ACKNOWLEDGMENTS

The author thanks Ms. Mary Gail Engle for providing the electron micrographs that were used in the EM atlas, as well as Drs. Brian MacPherson and Marilyn Duncan for their helpful editorial comments and to students in the medical class of 2005 for their participation in this study.

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