Primary Siwi-piRISC is produced through the primary pathway (Nishida et al, 2018). The piRISC binds transposon mRNAs and cleaves them into pieces. Of those, one fragment is loaded onto unloaded Ago3, which is anchored to mitochondrial Papi with help from Vasa (Nishida et al, 2015). Zuc processes the RNA to give rise to mature Ago3-piRISC. Vret associates with Ago3-piRISC and assembles Ago3 bodies. During this process, the Vret−Ago3-piRISC complex binds transposon transcripts in the antisense orientation. Unloaded Siwi enters into the bodies and joins the Vret−Ago3 complex. In this context, Ago3-piRISC and unloaded Siwi are held in close proximity with assistance from two (or more) Vret molecules, facilitating secondary Siwi-piRISC production in the ping-pong cycle. 