Domain: Healthcare — Pathophysiology
Target concept: Cellular Morphological Changes in Hypertonic Dehydration

Video generation prompt: Place red blood cells in a hypertonic saline solution and dynamically observe their morphological changes under an optical microscope for 30 seconds.

Evaluation guide:
(i) Target concept: Osmotic water efflux from erythrocytes in hypertonic extracellular fluid leading to plasma membrane deformation.
Minimum mechanism: (1) Extracellular solute concentration > intracellular solute concentration; (2) Cell membrane is selectively permeable to water but not solutes; (3) Water moves out along osmotic gradient; (4) Cytoplasmic volume reduction exceeds membrane elasticity limit → buckling and spike formation.
(ii)Storyline: [Phase 1] Stable biconcave RBCs suspended in isotonic medium, visible as uniform discs with central pallor; [Phase 2] Hypertonic solution contacts RBCs at liquid interface, no delay, no mixing ambiguity; [Phase 3] Within same continuous view, RBCs lose central pallor → edges thicken → develop angular protrusions → fully crenated; [Phase 4] All changed cells remain intact (no lysis, no aggregation); [Perspective constraint] Fixed microscope field-of-view with shallow depth: only cells at focal plane change; [Visibility constraint] No occlusion, no glare, no debris obscuring cell contours; change must be resolvable at 40x-equivalent magnification.

Manual:
Experimental Procedure
1. Place a drop of isotonic saline containing suspended red blood cells onto a clean microscope slide.
2. Add a small volume of hypertonic saline solution to the edge of the drop.
3. Immediately observe under 40x objective while capillary action draws hypertonic solution into the mixture.
Observation of Experimental Phenomena
Red blood cells transition continuously from smooth biconcave discs to shrunken, spiky (crenated) forms within seconds of hypertonic exposure.
Summary of Experimental Principles
In hypertonic solution, water exits red blood cells via osmosis, causing cytoplasmic shrinkage and plasma membrane buckling—manifesting as crenation, a hallmark morphological change in hypertonic dehydration.

Prompt Grounding rubric:
level_1: No red blood cells appear anywhere in the clip; no container of saline solution is shown; no microscope-style field of view is depicted; there is no action of placing cells into a solution; the scene has nothing to do with observing blood cells under a microscope.
level_2: A container and/or a circular microscope-style field of view appears, but any red blood cells shown are not recognizable as biconcave discs (they look like blurred blobs or the wrong shape/size); the saline solution is not visibly present, or nothing marks it as present; there is no depiction of cells being placed into or contacting the solution.
level_3: Red blood cells are shown as identifiable biconcave, disc-shaped objects; a transparent container holding liquid is visible; a microscope-style circular field of view (framing suggesting an eyepiece or focus ring) is established; the cells are shown entering the solution as a discrete action (for example, descending from a pipette tip into the liquid); but exactly when the cells reach the solution, or how they are spatially arranged relative to it, is unclear.
level_4: Everything required for level 3 is shown, and in addition the red blood cells are placed into a clearly defined saline solution inside a transparent container; the microscope-style framing stays consistent for the whole clip; the moment the cells enter the liquid is shown unambiguously (for example, visibly crossing the liquid surface from above); no unrelated objects or actions contradict what the posted_prompt describes.
level_5: Everything required for level 4 is shown, and in addition: the microscope view shows the grain and shallow depth of field expected of a real microscope field rather than a plain zoomed-in shot; the cells begin visibly changing shape at some point before the clip's 30-second observation window ends, matching the posted_prompt's stated duration; the entire sequence stays within one fixed microscope viewpoint with no cuts, zooms, or angle changes.

Scientific and Causal Correctness rubric:
level_1: The red blood cells show no shape change at all, or instead of shrinking they swell or burst, or they vanish from view; the surrounding liquid's effect looks isotonic or hypotonic (cells stay round discs or become swollen spheres rather than shrinking); there is no visible connection between contact with the solution and any change in the cells' shape.
level_2: The cells change shape in a way that contradicts a hypertonic response: for example they swell, rupture, or clump together without ever shrinking; or their shape changes before they ever touch the solution; or the solution is missing from view at the moment the cells change; or the cells first enlarge and only later shrink (the wrong order for this mechanism).
level_3: The cells visibly touch the saline solution and afterward begin losing their smooth biconcave profile, developing scalloped or spiky edges consistent with crenation; the change proceeds steadily in one direction (toward more spiky, not back toward smooth); however, the starting biconcave shape is not entirely clear, or the final spiky shape is not fully developed by the end of the clip.
level_4: The cells start out clearly biconcave and intact before touching the solution; after contact, they progressively lose their central pale spot and develop increasingly angular, irregular edges; none of the cells reverses direction, oscillates between shapes, or shows a non-crenation artifact such as folding or clumping; every visible cell follows the same shrinking, spiky-edge trend.
level_5: Every visible cell moves continuously and together from a clearly biconcave disc, to loss of the central pale spot, to a fully spiky (echinocyte) outline by the end of the sequence; no cell keeps its original smooth disc shape at the end; there is no artifact that could be mistaken for shape change (no blur or rendering noise standing in for real spikes); only cells shown touching the solution undergo this change: any cell that never contacts the liquid stays a smooth biconcave disc.

Spatiotemporal Consistency rubric:
level_1: Cells jump from one place in the frame to another with no visible path between; the container disappears and then reappears; the picture's brightness suddenly changes to a completely different look; the microscope field jumps to a different area or spins; cells flicker in and out of view while supposedly moving.
level_2: Cells move in a jerky, stop-start way rather than smoothly; the container's edge visibly warps or bends; the light or shadow changes noticeably between one part of the clip and another; the microscope field drifts or wobbles enough to be distracting; cells appear or disappear abruptly without fading or being blocked from view.
level_3: Cell motion is generally smooth and continuous; cells descend into the solution along a believable path; the container stays in the same place and shape throughout; the overall lighting and sharpness of the picture stay close to constant; no shapes break apart (no cells tearing, no cracks in the container); small amounts of jitter or brief soft-focus moments may occur but never hide the cells' shape changes.
level_4: Everything required for level 3 is shown, and in addition cells descend at a steady, believable pace and keep their shape intact as they settle into place; the container's outline stays rigid and undistorted; the lighting stays even across the whole clip; the cells being observed stay in sharp focus throughout; there is no flickering, warping, or mismatched depth cues between frames.
level_5: Everything required for level 4 is shown, and in addition the cells' descent looks perfectly smooth with no sudden speed changes; the container walls stay visually clear and undistorted rather than warping or smearing; the microscope field stays completely still with no drifting, tilting, or zooming; the area in focus stays the same throughout, matching where the cells are observed; there is no strobing, ghosting, or repeated-frame look anywhere in the motion.