Theory 24/Cellular/Cell division
Spindle Orientation Is a Tension Ratio
The claim
The orientation of a dividing cell is set by the ratio of cortical tension anisotropy to spindle forces, so equal forces produce a random axis.
01Mechanism
The spindle aligns with the steepest tension gradient; when anisotropic cortical tension is weak, the spindle takes the orientation of least resistance.
02Prediction
Orientation should track the ratio.
03Refutation
Orientation tracking spindle force alone would remove cortical tension.