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Chemotaxis Parameters

To quantify chemotaxis and migration, several values can be generated by using the Chemotaxis and Migration Software Tool. One value is the center of mass. A second is the x and y Forward Migration Indices. Both of these values are a measure of directed cell migration. A third value is directness, but this may not necessarily indicate a chemotaxis effect.

: i is the index of the different single cells. The first cell has the index 1, the last one n.

: index of the cells

Center of Mass (M_end)

The center of mass represents the averaged point of all cell endpoints. Its x and y values indicate the direction in which the group of cells primarily traveled.

x and y Forward Migration Indices
(x_FMI, y_FMI)

The x_FMI and y_FMI represent the efficiency of the forward migration of cells, in relation to the x- or y- axis. The larger the index on an axis, the stronger the chemotactic effect is on this axis. For simplification, it is assumed that either the x-axis or the y-axis is parallel to the direction of the chemotactic gradient.

For simplification, one can also define a direction parallel to the gradient (║) and a direction perpendicular to the gradient (┴). By this, one value for the FMI ┴ , and one for the FMI║, is created.

: directionality of one single cell

: averaged directionality of all cells

Directness (D)

The directionality is calculated by comparing euclidean and accumulated distance. It is a measure of the directness of the cell trajectories. A directionality of D --> 1 equals a straight-line migration from start to endpoint.