NOTE for VISITORS:  Only students at SIU School of Medicine have physical access to the actual microscope slides referenced here.

Instructions for examining Self-Assessment Slides

Hints for individual slides.

• Ask for slides from the MRC.
• Work together in small groups.  This job is challenging enough that it helps to pool your strengths.
• Begin by reviewing these two pages:
• Step-by-step guide for slide viewing.
• What are the most common patterns of tissue organization?


• Most of the self-assessment 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.  
   
• Be aware that pathology or post-mortem changes may distort expected appearances.  
  • Some post-mortem specimens may shed epithelial cells from exposed mucosal surfaces.
  • Other specimens (notably pancreas) will self-digest into mush.
  • In this exercise, the hints for each slide will inform you if there is significant pathology; otherwise, most of the self-assessment specimens are "within normal limits" for samples from deceased patients.
     
• Each slide includes one or more distinctive clues (sometimes small and/or obscure) which should enable recognition of the source organ.
   
• If you begin examining these slides before you have completed a systematic study of histology, you should expect that some (or most) of the specimens will still be unfamiliar.  So don't worry if a slide seems completely alien.  Look among the specimens for any that you might have already studied, basing a tentative identification on obvious unaided-eye features such as size, shape, presence or absence of layers, etc.
• See What are the most common patterns of tissue organization?


• Slides may come from any organ of the body, not just those from organ systems associated with the name of the slide box.
   
• Examine the entire specimen.
  • Scan first with your unaided eye (or with an inverted microscope ocular).  
    • Note size and shape of the specimen. This by itself will substantially narrow the field of possibilities.
    • Note whether the specimen appears layered or relatively uniform; this should narrow the field still further.
    • Notice all areas that have differing textures or staining characteristics; 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.
  • Use a high power objective primarily to examine specific details.  Do not try to survey the entire specimen at high magnification, since significant areas are too easy to overlook.  (Remember the aphorism, "High power objective, low-power histologist.")
     
• 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 not yet have considered the actual correct identification.
   

Comments and questions: dgking@siu.edu

SIUC / School of Medicine / Anatomy / David King

https://histology.siu.edu/SAQslidehints.htm
Last updated:  28 December 2024 / dgk