Mobile arrays of vacuole ripples are common in plant cells.

In tobacco (Nicotiana tabacum L.), a structure frequently interpreted as endoplasmic reticulum, was clearly identified as a set of ripple-shaped protrusions of the vacuole into the surrounding cytoplasm. The occurrence in other species suggests that these ripples might be common in vacuolated plant cells. The apparent mobility of the ripples depends on the integrity of the F-actin network. This raises questions concerning the precise composition and architecture of the cytoplasm/vacuole border. The stereotypic concept of the central vacuole as a kind of inflated balloon with a smooth surface has to be debated.