Light and electron microscopical studies were carried out in order to characterize the blood cells of the bivalve mollusc, Scapharca inaequivalvis (Bruguière). Cytochemical techniques were also used to investigate peroxidase, phenol oxidase and lysosomal enzyme activity in the cells. Four types of blood cell were found: the more numerous erythrocytes and three populations of white blood cells. The red blood cells were found to be nucleated and contained dense cytoplasmic granules and various organelles; a well-developed Golgi apparatus, rough endoplasmic reticulum, variable numbers of mitochondria and fine cytoplasmic microtubules were observed. The white blood cells were generally smaller and less frequent. The type 1 cells possessed variable numbers of acidophilic, cytoplasmic granules and showed a high degree of vacuolation. The highly granular cells showed more extensive pseudopodia, perhaps indicative of intense phagocytic activity. The type 2 cells were basophilic and possessed few or no cytoplasmic granules. The type 3 cells were infrequently seen; they were relatively large and packed with large, dense, acidophilic, membrane-bound granules. Peroxidase and arylsulphatase activity was found to be present in the type 1 and 2 white blood cells and in the cytoplasmic granules of the erythrocytes. No phenol oxidase activity was detected.

No abstract

No abstract

The ultrastructure of Rana dalmatina tadpoles' gonads is described during two early stages of development: the primary and the secondary undifferentiated condition. The gonadal bud structure in the first stage of differentiation is characterized, and it is clearly demonstrated that the cortex and the medulla are lined by an uninterrupted basal lamina along the margin adjacent to the primary cavity. The basal lamina that lines the cortex is a continuation of the one delimiting the somatopleura. In the second stage, it is shown that the medulla delaminates to form a secondary gonadal cavity known as the ovarian pocket, and that the cortex contains early germ cells, both isolated and undergoing mitotic division, corresponding to a germinal epithelium. In addition the diplotenic oocytes form a distinct layer within the primary gonadal cavity between the cortex and medulla. Each of the three layers (germinal epithelium, diplotenic oocytes, and hollow medulla) is delimited by its own basal lamina. The ultrastructure of the different germ and somatic cells is described.

No abstract