Figure 1. Vacuolar rupture during the final stages of yeast sporulation. (A) Transmission electron micrograph of a cell executing PND. Black arrows indicate loss of vacuolar membrane continuity in the mother cell during spore development. Spores (S), uncellularized nucleus (N) and vacuole (V) indicated. Scale bar: 500 nm, adapted from Eastwood et al., (2012). (B) Summary of our model. The mother cell vacuole (V) undergoes disintegration after the encapsulation of nuclei (red) for spore packaging. Nuclei not selected as spores are subject to destruction upon the permeabilization of the vacuole and release of its lytic contents. We depicted an ascus forming two spores while destroying the remaining two, but we find the disintegration of the vacuole always occurs at this stage of sporulation, irrespective of spore number. Yeast sporulation thus invokes mega-autophagy, or the rupture of the vacuole, as part of a developmental program dedicated to breaking down the contents of the mother cell.