Domain: Healthcare — Pathology
Target concept: Atrophy (disuse atrophy)

Video generation prompt: A skeletal muscle tissue specimen in a long-term disused state was placed on the experimental table, and the morphology of muscle fibers was observed under the optical microscope.

Evaluation guide:
(i) Target concept: Disuse atrophy manifests as reversible, non-necrotic reduction in skeletal muscle fiber size without architectural disruption.
Minimum mechanism: Reduced mechanical loading over time → downregulation of mTOR pathway → net proteolysis > synthesis → myofibrillar volume loss → fiber caliber reduction while sarcolemma and basal lamina remain intact.
(ii)Storyline: Frame 0–2: Specimen placed centrally on table; microscope lowered into position above it. Fixed viewpoint, no motion blur. Frame 3–6: Stable close-up view simulating microscope field: thin, fairly uniformly reduced fibers dominate the visual field; pale hue confirmed; no inflammatory cells or connective tissue invasion. Frame 7–10: Sustained focus on fiber morphology: consistent thinness, parallel alignment, intact striations, and uniform interstitial expansion, all visible without occlusion, distortion, or lighting interference. Perspective remains strictly top-down (microscope view), never cutting to macro or hand-level shots.

Manual:
Experimental Procedure
1. Place skeletal muscle tissue specimen (disused atrophy) on clean experimental table.
2. Position optical microscope directly above specimen.
3. Observe muscle fiber morphology through microscope eyepiece.
Observation of Experimental Phenomena
Muscle fibers appear markedly thinned with a fairly uniform reduction in caliber across the field (no angular or clustered small-fiber groupings, which would instead suggest denervation); increased interstitial space; pale pink to whitish color; no inflammation or necrosis.
Summary of Experimental Principles
Disuse atrophy causes reduction in myofiber cross-sectional area due to decreased protein synthesis and increased proteolysis, driven by reduced mechanical loading rather than loss of nerve supply; fibers shrink but retain structural integrity, rounded-to-polygonal outline, and alignment.

Prompt Grounding rubric:
level_1: No skeletal muscle specimen, no experimental table, and no optical microscope appear anywhere in the frame; no action of placing tissue or observing it is depicted.
level_2: At least one, but not all three, of the required elements (specimen, table, microscope) is present, for example a microscope and table appear with no tissue specimen visible, or a specimen appears with no table or microscope in the shot; no placement or observation action is shown.
level_3: The skeletal muscle specimen sits on the experimental table, and an optical microscope is also present in the same shot positioned near the specimen, such that the scene reads as 'specimen about to be examined under this microscope'; specimen is not floating off the table or set apart from the microscope.
level_4: All elements from score 3 are present AND the microscope's objective lens/head is visibly angled or lowered toward the specimen rather than pointed elsewhere; the specimen sits roughly centered under where the lens is aimed; the shot then holds a close-up, top-down magnified view of the specimen's muscle-fiber morphology (as seen through the microscope), not just the external setup; no other object blocks the view of either the specimen or the microscope.
level_5: All elements from score 4 are present AND the specimen sits directly beneath the microscope's objective lens with no visible gap or offset suggesting it is not the object being viewed; the tabletop beneath the specimen is unbroken and flat; the transition from the external setup view to the magnified fiber-level view stays within the same fixed top-down perspective, with no cut to a macro or hand-level shot and no scale or angle mismatch making one view look pasted onto the other; there is no doubt about what is being observed.

Scientific and Causal Correctness rubric:
level_1: Muscle fibers appear at normal, healthy caliber with uniform rounded-to-polygonal cross-sections; no fiber shrinkage of any kind is visible; the specimen retains a healthy reddish-pink hue with no pallor, i.e., it looks indistinguishable from normal, actively-used muscle tissue.
level_2: Muscle fibers are visible but show no consistent size reduction relative to normal muscle: fiber sizes look either uniformly normal or randomly variable without an overall shrinkage trend; the specimen shows no shift toward pallor, so no atrophic pattern is legible.
level_3: Most muscle fibers in the field are visibly smaller in cross-section than normal skeletal muscle, and the size reduction is broadly uniform across the field rather than isolated to scattered fibers; fibers retain their normal rounded-to-polygonal outline (not angular or wedge-shaped); overall specimen tone is paler/duller than healthy reddish-pink muscle, consistent with atrophic tissue.
level_4: All elements from score 3 are present AND the small fibers are evenly interspersed with only mild caliber variation from one fiber to the next (there is no clustering of small angular fibers next to normal-sized ones, which would instead signal denervation/neurogenic atrophy rather than disuse); interstitial space is modestly widened in proportion to the uniform shrinkage, not concentrated around isolated fiber clusters; no inflammatory infiltrate, fibrotic bands, or fat infiltration are visible.
level_5: All elements from score 4 are present AND fiber outlines stay smooth and rounded-to-polygonal everywhere in the field (no angular or wedge-shaped fibers, which would point to neurogenic rather than disuse atrophy); parallel fascicular alignment is preserved across the whole specimen; pallor is even across the field with no localized red or hemorrhagic patches; the overall picture reads as uniform disuse-pattern shrinkage with no cues of denervation, inflammation, or other competing pathology.

Spatiotemporal Consistency rubric:
level_1: The muscle specimen or the microscope disappears from view or instantly jumps to a different spot on the table between frames; the tabletop visibly warps, tears, or changes shape mid-sequence; illumination flips between bright and dark with no plausible transition; the specimen appears to move or spin on its own with no cause shown.
level_2: One clear spatiotemporal break occurs: the specimen's position on the table shifts between shots, the microscope's angle or height changes inconsistently, the specimen's cast shadow on the tabletop swings to a different side even though neither the microscope's overhead light nor the specimen itself has moved, or the view snaps from sharp focus to blurred (or vice versa) with no visible focusing motion.
level_3: The specimen and microscope each stay in one fixed spot on the table across the whole sequence, with no jumping, spinning, or resizing; the specimen's cast shadow on the tabletop, produced by the microscope's overhead illumination, keeps the same side and softness from the first frame to the last; no part of the table, specimen, or microscope tears, clips through another object, or briefly vanishes.
level_4: All elements from score 3 are present AND the camera framing never pans, tilts, or zooms: the top-down microscope-field view is held fixed throughout; there is no visible flicker or sudden brightening/dimming of the scene between frames; the visible fiber pattern within the specimen stays legible and does not swim or dissolve into noise as frames progress.
level_5: All elements from score 4 are present AND the surface texture of the specimen looks consistent from the first frame to the last (no sudden change in how detailed or smooth it appears); the microscope's field of view and the specimen remain at a matched, consistent focus level throughout (both sharp, or both softly blurred together, never one sharp while the other blurs independently); across the full sequence, nothing about the framing, lighting, or object positions changes in a way a viewer would notice as a cut or glitch.