Phagocytosis by hemolymph cells of the land slug, Incilaria fruhstorferi Collinge (Gastropoda: Pulmonata)

Phagocytosis by hemolymph cells of the land slug, Incilaria fruhstorferi Collinge, were studied with the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM). The fate of foreign materials, i.e., sheep red blood cells (SRBC) and latex beads, introduced into the hemocoel of the slug were followed. Certain hemocytes named as Type I cell were involved in spontaneous cyto-adherence while both Type II and III cells were not observed to adhere to foreign materials. SRBC and latex beads (luminal diameter 0.79 micron) were phagocytosed and latex beads (luminal diameter 15.8 micron) were engulfed by Type I cells. In vitro phagocytosis experiments showed that SRBC formed the rosette structure surrounding a Type I cell and both SRBC and latex beads (luminal diameter 0.79 micron) were swallowed by Type I cells in vivo. The plate-like structures with long fine fibers attached the latex beads. The latex beads were often seen deep in the aggregates of plate-like structures.