Longitudinal axis thickenings in whole-mount spreads of synaptonemal complexes from Tradescantia

The whole-mount spreading technique was used to examine the chromosome complement in ten zygotene nuclei of Tradescantia ohiensis var. paludosa. Spread preparations have normal synaptonemal complex (SC) morphology. Neither kinetochores nor recombination nodules were regularly visible. Cloudlike structures (LFSs) 2–6 m in diameter were sometimes associated with SC and with unsynapsed lateral components (LCs). They differed in number and location in different nuclei. Thickenings of the lateral elements and LCs were observed in mid through late zygotene nuclei. These longitudinal axis thickenings (LATS) were distributed fairly uniformly amongst the chromosomes and occurred in both synapsed and unsynapsed regions. There was a stage-dependent increase in the number and size of LATS. They were nonrandomly distributed along the length of a chromosome, being more frequent in synapsed areas, especially near junctions with unsynapsed regions.