Recombination nodules (RNs) are ellipsoidal particles lying on the central element of the synaptonemal complex (SC) during zygotene and pachytene of meiosis in eukaryotic organisms. RNs seem to reside at the sites of reciprocal recombination events in late pachytene nuclei. We are studying the temporal development, spatial distribution, and biochemistry of RNs and SCs.