FIG 1.

Schematic representation showing the transovarial transmission process for the bacterial symbionts of representative auchenorrhynchan insects. In mature females, “Ca. Sulcia” and the coinfected symbiont leave the bacteriome (B) for the hemolymph (He), invade the posterior pole of the oocytes (O), migrate through the follicular epithelium (FE) into the perivitelline space (PS), and finally form a characteristic symbiont ball (SB) at the posterior pole of the oocytes. BS, bacteriome sheath.