Domain: Healthcare — Pathology
Target concept: Calcification (arterial wall calcification)

Video generation prompt: A aged aortic wall tissue sample is placed on the experimental table, and observed under the microscope after Von Kossa staining.

Evaluation guide:
(i) Target concept: Visualization of arterial wall calcification in aged aorta using Von Kossa histochemistry.
Minimum mechanism: Silver ions must ion-exchange with the phosphate/carbonate anions of the calcium salt deposits, forming insoluble silver phosphate/carbonate localized to the calcified foci; this silver salt is then photochemically reduced to black metallic silver under UV or bright light exposure; tissue architecture must preserve medial layer identity for anatomical specificity.
(ii)Storyline: [Frame 0–2] Aged aortic wall tissue section is placed centered on a glass slide on an experimental table. [Frame 3–5] Slide is loaded onto microscope stage; microscope remains stationary with fixed viewpoint. [Frame 6–8] Microscope view transitions to high-magnification field showing tissue; black granular deposits appear exclusively within concentric medial layer boundaries. [Frame 9–10] Final stabilized view confirms deposit localization, tissue stratification, and staining contrast, all under consistent lighting and fixed spatial framing.

Manual:
Experimental Procedure
1. Place aged aortic wall tissue section on clean glass slide.
2. Apply Von Kossa stain (silver nitrate solution) and expose to UV or strong light.
3. Rinse, counterstain with nuclear fast red, mount under coverslip.
4. Position slide on microscope stage and observe at 100× magnification.
Observation of Experimental Phenomena
Black or dark brown granular deposits appear exclusively in the tunica media layer of the arterial wall; surrounding tissue stains pink-red; elastic laminae appear fragmented and irregular.
Summary of Experimental Principles
Von Kossa staining detects calcium deposits indirectly: silver ions (Ag⁺) exchange with the phosphate and carbonate anions bound to calcium in the mineralized deposits, forming insoluble silver phosphate/carbonate in place of the calcium salts; exposure to UV or strong light then photochemically reduces this silver salt to black metallic silver (Ag⁰), while the freed calcium ions wash out during processing. Arterial wall calcification occurs preferentially in the aged tunica media due to elastin degradation and dystrophic mineralization.

Prompt Grounding rubric:
level_1: No aortic tissue sample is shown; or no table is shown; or no microscope or glass slide is visible; nothing suggests a staining or observation setup.
level_2: A tissue sample sits on a table-like surface, but it doesn't look like an aged arterial wall (e.g., it appears uniform and unlayered rather than a blood-vessel wall); or no microscope is present; or there's no slide and no sign of any staining step.
level_3: An aged aortic wall tissue sample sits visibly on the experimental table; a light microscope is present and aimed at the sample; a glass slide holding the tissue is visible on the microscope stage; the tissue, table, microscope, and slide all match the types described in the setup.
level_4: Level 3's requirements still hold, and additionally the tissue sits centered on the slide, the slide sits properly seated on the microscope stage (not floating or off to the side), and the microscope's optical path is aimed at the slide; no unrelated object (gloves, extra reagent bottles, pipettes) appears in the shot.
level_5: Level 4's requirements still hold, and additionally the final microscope view shows only the tissue on the slide, filling the field seen through the objective lens; the table surface stays fully visible and continuous beneath the microscope's base; nothing floats, duplicates, or sits misaligned (e.g., the slide is never shown detached from the stage, and the microscope is never shown tilted away from the slide).

Scientific and Causal Correctness rubric:
level_1: No black or dark brown deposits appear anywhere in the tissue; the tissue looks uniformly pink, blue, or unstained; there's no visible contrast between any region of the tissue.
level_2: Black or dark brown deposits appear, but they sit on the glass slide or table rather than on the tissue itself; or they appear on the tissue with no relation to the layered structure of an arterial wall (no sign of a distinct middle layer).
level_3: Black or dark brown granular deposits appear only on the arterial wall tissue, and they sit within the tunica media (the layered middle band of the vessel wall), appearing as a dense, concentrated band between the inner and outer boundaries of the tissue; the tissue shows aging-related features such as broken-up elastic fibers or uneven wall thickness.
level_4: Level 3's requirements still hold, and additionally the deposits stay confined to the tunica media with none spilling into the innermost or outermost layers; the three-layer structure of the arterial wall (inner, middle, outer) stays visually distinguishable; no black staining appears in the outer, collagen-rich layer alone.
level_5: Level 4's requirements still hold, and additionally the black deposits form sharply bordered clusters within the tunica media, matching the classic look of Von Kossa-stained calcification; the rest of the tissue shows the expected pink-red counterstain; no black staining appears where it shouldn't, such as inside cell nuclei or in the general cytoplasm away from the mineral deposits.

Spatiotemporal Consistency rubric:
level_1: The tissue appears on the slide, or the microscope appears, with no placement motion; the room lighting flickers violently; the slide spins past 90 degrees with no visible turning motion; the table surface cracks or warps between frames.
level_2: The tissue shifts position abruptly between shots with no motion shown connecting the two positions; the microscope's viewing angle changes suddenly (e.g., a front view cuts directly to a top-down view with no rotation shown); the slide appears to lift off the stage and then reattach; the shadow on the table switches to the opposite side between two consecutive frames.
level_3: A brief freeze of a couple of identical frames is allowed, along with a slight wobble in the microscope's focus adjustment or a slow, gentle shift in ambient lighting across the table, but the tissue, slide, and microscope otherwise stay in the same relative arrangement with no break in what object is where.
level_4: Level 3's requirements still hold, and additionally the tissue, slide, and microscope stay in the same relative positions throughout with no appearing/disappearing; the slide stays fully visible under the microscope at all times; the light source stays on the same side and at the same brightness throughout; any motion (such as a focus adjustment) is smooth rather than sudden or jerky.
level_5: Level 4's requirements still hold, and additionally any stage or focus adjustment moves smoothly from start to finish with no skipped frames; every object's edges stay sharp and stable rather than flickering or blurring in and out; the lighting and shadow positions stay exactly the same for the entire sequence; nothing in the shot appears to float free of the surface it should be resting on, consistent with the fixed camera viewpoint.