Preprophase band, apical curvature and cell division

Before division, microtubules position at the cortex of the vegetal cell along a band called preprophase band. This preprophase band disappears later but it indicates the anchorage on the cell cortex of the future division plane. The PPB follow geometric rules of positioning coined Errera rule; we show the apex curvature combined with the positioning rule strongly restricts the apical cell shape.