FIG. 2.

Symbiont infection in early embryos of the clones IS and AIST^IS. (A) A stage 8 embryo of clone IS; (B) a stage 8 embryo of clone AIST^IS; (C) a stage 12 embryo of clone IS; (D) a stage 12 embryo of clone AIST^IS. Green, red, and blue signals indicate B. aphidicola, S. symbiotica, and nuclei of host cells, respectively. Bars, 50 μm. At stage 8, embryos are infected with the symbionts, and at stage 12, a large syncytial cytoplasm harboring the symbionts cellularizes into many bacteriocytes. Developmental staging of A. pisum is according to reference 14.