The ultrastructure of hemolymph cells of the land slug, Incilaria fruhstorferi Collinge (Gastropoda: Pulmonata)

3 morphologically distinct hemolymph cell-types, Type I, II and III, were found in the hemolymph of the land slug, large Japanese native slug, Incilaria fruhstorferi Collinge. Type I cell, measuring approximately 35 microns in diameter, had extensive pseudopodia with supporting ribs and a kidney-shaped or lobulated nucleus. Sometimes it possessed long filopodia (approximately 50 microns) with branched fibers. It contained residual bodies, multivesicular bodies, Golgi apparatus, free ribosomes and glycogen-like deposits. Type II cell, approximately 5 microns in diameter, did not form large pseudopodia, had a higher nucleus to cytoplasm ratio. It contained scattered free ribosomes surrounding the round nucleus. Type III cell, approximately 75 X 15 microns, was a fibroblast-like cell. It contained microfibrils at the rim of perinuclear cytoplasm and possessed collagen-like fibers outside of the cytoplasmic membrane. Numerous plate-like structures, which had not been reported yet, were usually observed. They, measuring 1 to 5 microns in diameter, were oval, but when in contact with glass, they possessed long and fine fibers. They lacked nucleus.