Only cells with any sign of septum formation, regardless of its types (PS, primary septum; SS, secondary septum), and with no visible division scars were scored. The latter is to minimize possible mis-scoring of structures from previously formed septa.

An electron-translucent stripe originated from the bud–neck region was defined as one PS.

Number of cells with any PS divided by number of cells with any septum (PS or SS).

Number of cells with a PS spanning the entire bud neck divided by number of cells with any PS.

The angle between two lines starting from the base of a given PS was measured: one line is perpendicular to the mother–bud axis and the other connects to a site along the PS that yields the biggest angle (it could be at the tip or in the middle of the PS). Only cells with one or two PSs that extended at least one quarter of the bud–neck width were used for measurement (see also Fig. 5 D).