Immunostaining of leech central nervous system (CNS) using rabbit polyclonal anti-human C1qBP antibodies (green). Ganglia were analyzed immediately (A), 6 h (B, C), or 24 h (D) following injury. Microglial cell nuclei (white) were stained with Hoechst fluorescent dye to observe cell migration. (A) No anti-C1qBP immunostaining was detected at the lesion site and no microglial accumulation was observed. (B) At 6 h following injury, positive immunostaining was observed at the site of crush. Simultaneously, microglial cells progressively accumulated at the lesion site. (C) High magnification image of the injury site. Since all microglia nuclei are shown by Hoechst counterstaining (white), the anti-C1qBP immunostaining exclusively detects only some microglial cells. (D) At 24 h following injury, the number of microglial cells is much greater at the lesion site and stronger positive immunostaining is observed. (B', C', D') No immunostaining was observed using secondary antibodies alone as negative controls.