SPB insertion in cut7.24 mutant cells at 36°C. cut7.24 cells were grown at the permissive temperature until early-log phase when they were shifted to the restrictive temperature. 3 h later, samples were taken for transmission EM processing. (A–D) Micrographs of two consecutive sections of a mitotic nucleus are shown (A and B) alongside enlargements of relevant areas of both (C and D). In contrast to cut12.1 cells, both SPBs insert into the nuclear envelope. Microtubules (MT) from both SPBs run parallel and fail to interdigitate. White arrowheads indicate the SPBs. Bars: (A and B) 500 nm; (C and D) 100 nm.