Preparing SC spreads with RNs for EM analysis.

Recombination nodules (RNs) are associated with synaptonemal complexes (SCs) during early prophase I of meiosis. RNs are too small to be resolved by light microscopy and can be observed directly only by electron microscopy. The patterns of RNs on SCs can be analyzed using three-dimensional reconstructions of nuclei using serial thin sections, but this method is time consuming and technically difficult. In contrast, spreads of SCs are in one plane so all RNs in each set can be visualized simultaneously, and the patterns of both early and late nodules (ENs and LNs) can be analyzed far more easily than using sections. Here, we describe methods for preparing spreads of SCs and RNs from tomato primary microsporocytes on plastic-coated slides for visualization by transmission electron microscopy (TEM).