Hints for Self Assessment Slides

• Work together in small groups.  This job is challenging enough that it helps to pool your strengths.
   
• The SAQ slides come from autopsy specimens.
• These specimens are representative of actual clinical practice.
  • Fixation and staining, and the resulting cellular detail (or lack thereof), may not be as pretty as in textbook micrographs or commercially prepared slides.
  • Recognizable tissue features are present, even if they are not pretty.  
     
• Although most slides are stained with H&E, note that in each set of nine slides one slide is stained with PAS and one is stained with trichrome.
   
• Be aware that post-mortem changes may distort expected appearances.  For example, some post-mortem specimens may shed epithelial cells from exposed mucosal surfaces.  Some organs (notably pancreas) will self-digest into mush.  In this unit, the SAQ specimens are pretty much "within normal limits" for samples from deceased patients.
   
• Most specimens include several distinctive clues which should enable recognition of the source organ (but a couple may be more difficult).
   
• If you begin examining these slides before you have completed CRR, you should expect that some of the specimens will still be unfamiliar.  So don't worry if a slide seems completely alien.  You might profitably skip such slides, recording their numbers to revisit later, after you have studied all of the C, R, and R systems.
   
• Examine the entire specimen.
  • Scan first with your unaided eye (or with an inverted microscope ocular).  Notice all areas that have differing textures or staining characteristics, and make sure these are all examined microscopically.
  • With the lowest-power objective, carefully survey the borders of the specimen.  Distinguish between cut edges and natural surfaces.
  • Natural surfaces (mucosa, serosa, intima) often present distinguishing characteristics.
  • Also at low power, scan all solid areas.
  • Determine whether solid masses represent fibrous connective tissue, muscle (what kind?), lymphoid tissue, glandular tissue (what kind?), etc.
     
• Don't jump to a conclusion.  Treat specimen identification as you would diagnosis, gathering information and then formulating and testing hypotheses.
  • Describe basic tissue elements.  Your first response to any particular slide should be to list observations in the most basic, non-committal terms, and evaluate these observations in terms of personal confidence (i.e., reliability of your present observational skill).
  • List alternative hypotheses.  How many different possibilities are consistent with the most reliable of your observations?
  • Test each hypothesis.  Use your knowledge of organ structure to predict additional, confirmatory observations.  Make sure that such observations are then made objectively (i.e., not "imagined", or colored by expectations).  Look thoroughly for disconfirming features -- make sure that the entire specimen has been inspected and that all parts are consistent with your hypothesis.  (If you find yourself saying, "I think this is X, but I can't make sense of region Y," then maybe you should reconsider X.)
  • Intuitive recognition can be powerful.  But when mistaken, it can also be powerfully misleading.  Respect your limitations, and always follow the above steps.
     
• Once you have the correct identification, your confidence should grow with further examination and consideration.  If you continue to feel uncertain, you may have not yet considered the actual correct idenficiation.
   

  Hints for individual slides. DO NOT open these hints until you have first examined the slides.  Otherwise you will spoil the fun and thwart the purpose of the exercise.

Comments and questions: dgking@siu.edu

SIUC / School of Medicine / Anatomy / David King

http://www.siumed.edu/~dking2/crr/hints.htm
Last updated:  12 September 2005 / dgk