Fig. 5.

The mitotic and meiotic programs comprise related sequential cycles of global chromatin expansion and contraction, proposed to be cycles of expansional stress and stress relief. Four transitions of meiotic recombination (17) are indicated by I–IV. @ and!! symbolize analogies between prometaphase and telophase onset of the mitotic program and leptotene and diffuse stages of meiosis. @, appearance of silver-staining axis components along, and interaxis bridges between, sisters (mitosis, ref. 13) and homologs (meiosis, e.g., Fig. 4E) and chromosome destabilization in Sordaria spo76-1 (Fig. 14). (!!) Telophase onset and the diffuse stage both involve marked chromatin diffuseness and loss or destabilization of axial structures.