Light and electron microscopic observations on the spleen and the splenic leukocytes of the newt triturus cristatus

Abstract The newt spleen has an outer region, the red pulp, that consists of reticular fibres, reticular cells, and fixed macrophages forming a framework within which erythropoiesis occurs, and an inner region, the white pulp, consisting of a reticular framework containing predominantly lymphocytes. The fine structure of the following leucocytes, namely lymphoid cells, reticular cells, macrophage, haemocytoblasts, plasma cells and neutrophilic, basophilic and eosinophilic granulocytes is, in general, similar to that of the corresponding mammalian blood cells. However, in contrast, all the nuclei contain large numbers of interchromatin granules and a differentiated region termed the nuclear light‐staining zone because of its electron‐scattering properties. Furthermore the specific granules of the eosinophilic granulocytes are structureless whereas those of the basophilic granulocyte have crystalline regions. The structure and distribution of the granular, fibrillar, tubular and vesicular components of the cytoplasm of each cell type is described.