Light micrograph (LM) and scanning electron micrographs (SEM) showing the morphology and surface ultrastructure of the syzygies from the midguts of M. barneyi. (a,b) LM of syzygies. The syzygy contains two parts: primite (Pr) and Satellite (Sa). The nucleus (N) is visible in the middle of each individuals. The top structures in Pr (double arrowhead) and the connection (arrowhead) between the Pr and Sa were different between (a,b). (c) LM of a syzygy with three parts dyed by Meilan dye solution. (d–g) SEM showing the partial structure of syzygy; (d) the connecting part between protomerite (pm) and deutomerite (dm) in Pr.; (e) showing a recessed area (arrow) in the center of the top of the pm in (a); (f) higher magnification of the connecting part between Pr and Sa; (g) SEM of the posterior end of the Sa. (h,i) SEM showing the surface structure of syzygy; the ball-like structure was observed from the ruptured surface in (h). Scale bars (a,b) 100 μm; (c) 50 μm; (d–g) 10 μm; (h,i) 2.5 μm.