Observations on the Blood of the Australian Lungfish, Neoceratodus-Forsteri Klefft .1. Ultrastructure of Granulocytes, Monocytes and Thrombocytes

Abstract

The ultrastructure of eosinophils, heterophils, neutrophils, basophils, monocytes and thrombocytes is reported from the Australian lungfish, Neoceratodus forsteri. Eosinophils have an eccentric simple or bilobed nucleus and granules with an axial rod-like core similar to those of elasmobranchs, birds and mammals. Heterophils are polymorphonuclear with a prominent centrosome, and eosinophilic granules of many forms, some of which have a dense core that may become fragmented. Neutrophils are aiso polymorphonuclear, and are agranular or contain azurophilic granules and many dense core vesicles. Basophils have a central or eccentric nucleus and dense granules with a complex internal structure similar to those of mast cells of mammals. Monocytes have an indented or reniform nucleus, a few granules, rough endoplasmic reticulum and filiform surface projections; they contain secondary lysosomes and are similar to monocytes of other vertebrates. Thrombocytes contain granules with a fibrillar substructure similar to those of other lungfishes. Inter-relationsips of granulocytes, particularly between heterophils and neutrophils, are discussed.