BLOOD-CELLS OF THE ARCID CLAM, SCAPHARCA-INAEQUIVALVIS

Light and electron microscopical studies were carried out in order to characterize the blood cells of the bivalve mollusc, Scapharca inaequi valvis (Bruguiere). Cytochemical techniques were also used to investig ate peroxidase, phenol oxidase and lysosomal enzyme activity in the ce lls. Four types of blood cell were found: the more numerous erythrocyt es and three populations of white blood cells. The red blood cells wer e found to be nucleated and contained dense cytoplasmic granules and v arious organelles; a well-developed Golgi apparatus, rough endoplasmic reticulum, variable numbers of mitochondria and fine cytoplasmic micr otubules were observed. The white blood cells were generally smaller a nd less frequent. The type 1 cells possessed variable numbers of acido philic, cytoplasmic granules and showed a high degree of vacuolation. The highly granular cells showed more extensive pseudopodia, perhaps i ndicative of intense phagocytic activity. The type 2 cells were basoph ilic and possessed few or no cytoplasmic granules. The type 3 cells we re infrequently seen; they were relatively large and packed with large , dense, acidophilic, membrane-bound granules. Peroxidase and arylsulp hatase activity was found to be present in the type 1 and 2 white bloo d cells and in the cytoplasmic granules of the erythrocytes. No phenol oxidase activity was detected.