Fig. 1.

Cartoon summary of prophase I events in humans. The first four stages of prophase I are depicted (leptonema, zygonema, pachynema, and diplonema), together with the progression of synapsis events (shown by the localization of synaptonemal complex protein 3 [SYCP3; red], and SYCP1 [green]) and the appearance of major markers for recombination (colored circles). Homologous chromosomes, consisting of paired sister chromatids, are depicted as single looping lines radiating from the synaptonemal complex core. The timing of prophase I stages for male and female meiosis (in humans) is shown above the cartoon image, underscoring the temporal differences in prophase I progression between male and female germ cells. The complexity of synapsis and recombination events is greatly understated in this summary image, but some of the important genes are described here, all of which are components of key gene cliques within the HFOnet.