An indirect test for a role of the synaptonemal complex in the establishment of sister chromatid cohesiveness

The meiotic behavior of a special maize trisome was quantitatively observed at pachytene, metaphase I, anaphase I, prophase II, metaphase II and anaphase II. The data obtained are consistent with (but do not prove) the model that sister chromatid cohesiveness at anaphase I may be established during pachytene synapsis of the chromosome regions involved. The data suggest, however, that the normal prophase II maintenance of dyad integrity by cohesiveness of sister chromatid centromere regions does not depend upon prior synapsis of these regions, although monads separated from each other on the anaphase I spindle may be delivered to the same prophase II daughter nucleus. — The strands which some of the time connect sister chromatids which are separating equationally at anaphase I show a positive Feulgen staining reaction.