FIG. 3.

Electron microscopic analysis. (A) Extension of the forespore membrane was retarded in sst4Δ cells. Shown are representative images of a wild-type (wt) ascus and two sst4Δ azygotic asci after incubation on sporulation plates for 8 h. Many forespore membranes in sst4Δ asci remained unclosed. Bar, 1 μm. N, nucleus. (B) High-magnification images of spores in a wild-type ascus, two sst4Δ asci, and a pik3Δ azygotic ascus. Bubbles and membranous structures were found in sst4Δ asci (arrows), which were also observed in pik3Δ asci (arrowheads) (41). Strains used were TW747 (wt), MI619 (sst4Δ), and TP3 (pik3Δ). Bar, 0.5 μm.