Microscopy is a practice, not a unit. Eight of the ten A&P unit packets use microscopes for histology identification, and one (Tissues) uses them as the central activity. Rather than duplicating microscopy rubrics across every unit, this protocol defines microscopy technique once — in one versioned place — for any unit that needs it.

What this protocol replaces

Earlier packets included an inline R4 Microscopy rubric per unit. Going forward:

• Each unit’s R4 references this protocol by name when the observable performance task is microscopy (Tissues, Integumentary, Endocrine, Reproductive).
• Units whose R4 is dissection or another performance task (Respiratory sheep lung, Urinary sheep kidney + urinalysis, Digestive sheep specimen, Cardiovascular sheep heart, Nervous System sheep brain, Musculoskeletal palpation/ROM) still grade microscopy via this protocol when applied to their R3 histology slides — just at lower formal weight.

Two scopes covered here

The two principles underlying everything below

Pre-use setup checklist

• Two-handed carry. Microscope carried with one hand under the base, one on the arm. No single-handed carries even across short distances.
• Cord and cable management. Cord uncoiled without yanking; routed away from bench edges and student pathways.
• Stage at lowest position. Coarse focus knob adjusted so stage is at maximum distance from objectives before any slide is loaded.
• Lowest-power objective in place. Scanning (4×) or low-power (10×) objective rotated into position before slide load. Never load with high-power or oil objective in place.
• Light source verified. Lamp on; intensity at mid-range; condenser raised to working position; iris diaphragm open enough for visible illumination.

Slide loading checklist

• Slide oriented coverslip-up. Specimen-side up; coverslip protects the objective from contact with the specimen.
• Slide centered over stage opening. Specimen positioned roughly over the light path before clamping.
• Stage clips engaged correctly. Clips lowered onto slide edges (not specimen); slide held secure but not stressed.
• No contact between objective and slide during loading. Stage at lowest position the entire time the slide is being placed and clamped.

Parfocal focusing sequence (5-point checklist)

• Coarse focus on lowest-power objective only. Stage raised toward objective using coarse knob with eye on the stage (not eyepiece) to confirm no contact; THEN look through eyepiece and lower stage with coarse knob until specimen comes into rough focus.
• Fine focus brings specimen into sharp view at lowest power. Specimen sharp; field bright but not glaring; iris adjusted for contrast.
• Specimen centered before objective change. Region of interest moved to center of field BEFORE rotating to next objective. The microscope is parfocal, so a centered specimen remains centered after objective change; an off-center specimen is lost.
• Objectives advanced in order with fine focus only after first change. 4× → 10× → 40×. After 4× or 10×, only fine focus is used. Coarse focus on 40× is the most common cause of broken slides.
• Stage lowered before changing back to lower power. When returning from 40× to 4× or 10×, lower the stage first to clear any oil or debris, then advance the lower objective.

Scanning the field

• Survey at low power before zooming in. At 4× or 10×, scan the entire prepared area in a systematic pattern (left-to-right rows, or spiral from center) before committing to a high-power view.
• Most representative area selected for higher magnification. Student articulates why the chosen area is representative (most cells visible, best stain, least artifact, etc.) before zooming in.
• Iris diaphragm and condenser adjusted at each magnification. Higher magnifications require more illumination + finer iris control to maintain contrast.

Oil immersion (when applicable)

• Oil applied directly to slide, not to objective. Single drop of immersion oil on coverslip directly above region of interest; objective lowered into oil; objective should NEVER touch a dry slide.
• Oil-immersion objective only at 100×. Lower-magnification objectives are NOT designed for oil; rotating a dry objective through oil ruins the lens.
• Cleanup after oil use. Oil objective wiped with lens paper (NEVER tissue or shirt sleeve) immediately after use; slide cleaned with appropriate solvent.

Bench drawings are graded on conventions and labeling, not on artistic skill. A clear stick-figure-quality drawing with correct labels passes; a beautifully shaded drawing with wrong labels does not.

Drawing conventions (6-point checklist)

• Pencil only. Pen smudges, can’t be corrected, and bleeds through to facing pages. Mechanical pencil preferred; standard #2 pencil acceptable.
• Single contour lines, no shading. Outlines represent boundaries between structures; shading represents interpretation and is not used in scientific drawing. (Exception: stippling is acceptable for indicating texture or stain density, but only when intentional and labeled.)
• Two-circle convention or labeled magnification. Either: (a) one circle for low-power overview + one for high-power detail of region of interest, both labeled, OR (b) single drawing with magnification clearly noted.
• Labels with leader lines, not arrows through structures. Lines drawn from label to structure edge, ending precisely at the structure being labeled. Labels written horizontally, not at the angle of the leader line.
• Magnification recorded as total. Total magnification = ocular × objective (e.g., 10× ocular × 40× objective = 400×). Recorded as “400×” in the drawing legend.
• Stain noted. H&E unless otherwise stated (most common). Special stains (PAS, Masson trichrome, silver, elastic) noted explicitly.

Required labeling per drawing

• Specimen identification (tissue type or organ)
• At least two named structures visible in the field
• Total magnification
• Stain (H&E unless otherwise stated)

Anchor exemplars

End-of-session storage checklist

• Lowest objective rotated into position.
• Stage lowered to maximum distance.
• Slide removed and returned to slide tray. Oil cleaned from slide if used.
• Light source off. Iris closed if course policy.
• Cord wrapped per station convention.
• Dust cover replaced. If station has one.

End-of-session storage is part of the R4 score. A student who conducted excellent microscopy and then left the equipment in poor condition has not completed the practice.

Dissecting (stereo) microscopes are used for low-magnification (typically 5–40×) viewing of three-dimensional specimens that won’t fit under a compound microscope. The principles are similar to compound microscopy but with key differences in lighting, working distance, and what counts as a bench drawing.

What’s different from compound microscopy

• Reflected light, not transmitted. Specimen is viewed from above; light source illuminates the specimen surface. Some scopes have both transmitted and reflected — choose based on specimen.
• Larger working distance. Typically 50–150 mm, allowing dissection tools to be used while observing.
• Three-dimensional view. Two slightly offset light paths give depth perception (which compound scopes lack). Used for surface anatomy, dissection guidance, gross-specimen examination.
• No oil immersion, no slide. Specimens placed directly on stage; slides are unusual.

Setup checklist (4-point)

• Stage cleared and clean. Previous specimen debris removed.
• Specimen positioned with optimal lighting. Top light for opaque specimens (most A&P uses); bottom light for translucent or wet preparations.
• Lowest magnification used first. Survey whole specimen before zooming in. Zoom range varies by model (commonly 0.7×–4.5× objective range).
• Eyepiece spacing adjusted to user. Both eyes see one fused image, not two overlapping circles. (This is the dissecting-microscope analog of parfocal adjustment.)

Bench drawing for dissecting microscope

Dissecting-microscope drawings are typically:

• Larger and simpler than compound drawings. The structures are bigger and have more depth.
• Focused on spatial relationships. Show how structures connect and where they lie relative to each other.
• Labeled with magnification noted. Magnification typically given as the eyepiece × objective product, or simply “dissecting scope” with approximate magnification range.
• Often paired with an unscaled diagram. A free-hand diagram with arrows indicating direction or movement can complement the magnified drawing.

Common A&P uses

• Sheep brain external surface (cranial nerve stumps, sulci/gyri overview)
• Sheep heart external surface (coronary vessels, great vessels)
• Fetal pig dissection guidance
• Bone surface features at low magnification
• Preserved botanical specimens in associated coursework

Student: ______________________________________    Section: _______________    Date: _______________    TA: _______________    Unit: _______________

Compound microscope (when used this session)

Dissecting (stereo) microscope (when used this session)

Microscopy R4 overall

For units that grade microscopy as their R4 (Tissues, Integumentary, Endocrine, Reproductive): pass requires Compound (CM) overall pass. Pass on Dissecting (DM) is also required if dissecting microscope was used in the session.

For units whose R4 is dissection or another performance task: microscopy is graded informally against this rubric during R3 histology assessment, with notes captured for coordinator follow-up if technique is below standard.

When this protocol is the primary R4 rubric

For these units, microscopy is the central performance task and R4 is graded entirely against this protocol:

• Tissues — the foundational unit; this is where students learn microscopy formally for the first time
• Integumentary
• Endocrine
• Reproductive

When this protocol applies informally

For these units, R4 grades a different performance task (dissection, palpation, performance measurement). Microscopy technique is observed during R3 histology and graded against this protocol, but at lower formal weight; failures here become coordinator follow-up items rather than a student’s R4 grade for the unit.

• Cardiovascular (sheep heart dissection is R4)
• Nervous System (sheep brain dissection is R4)
• Musculoskeletal (palpation + ROM is R4 — minimal microscope use)
• Respiratory (sheep lung + spirometry is R4)
• Urinary (sheep kidney + urinalysis is R4)
• Digestive (sheep specimen dissection is R4)

If a student takes a unit without prior microscopy training

Some students arrive at A&P having transferred from a program that didn’t include the Tissues unit, or take individual units out of sequence. For those students:

• The first session of any microscope-using unit includes a 30-minute microscopy refresher run by the coordinator or trained TA, using this protocol as the curriculum.
• The first R3 histology in the unit is graded but does not count toward bundle thresholds; it is a calibration item.
• Subsequent R3 items count normally; the student is expected to have caught up on technique by the second session.
• A student who fails to develop minimum microscopy competency after the refresher + one calibration session is referred to the coordinator for one-on-one coaching before R3 grading continues.

Equipment maintenance triggers

The TA spot-check audit (per the TA Calibration Protocol) includes microscope condition. Lenses found dirty, oil residue found, stages found in raised position with slides loaded — all are documented and either (a) addressed via TA coaching if pattern, or (b) referred to lab manager if equipment-condition pattern across multiple stations.

Versioning

This protocol versions independently of the unit packets. When microscopy technique standards evolve (new equipment, updated lab safety guidance, new conventions in published lab manuals), only this document changes; unit packets reference it by name and inherit the update automatically.