腔肠动物的细胞 Longitudinal ofibrils Epitheliomuscular Filament Epidermis Interstitial Mesoglea cell Barb Cnidocil Gastrodermis Operculum Gland cell Cnidocyte Gastrovascular Sensory Nutritive. cell muscular cell Discharged Undischarged Circular myofibrils nematocyst nematocyst Cross section of hydra腔肠动物的细胞 back