Light- and Electronmicroscopic Observations on the Blood Cells of the Atlantic Hagfish,Myxine glutinosa (L.)

In the blood of Myxine glutinosa three cell lines may be distinguished: erythrocytes, granulocytes and agranulocytes. The erythrocytes are remarkably large, oval and nucleated. They are well defined in all their developmental stages by a characteristic micropinocytosis. They originate from blast cells which proliferate in the circulating blood. The blast cells probably form from agranulate stem cells of the intestinal myeloid tissue. The granulocytes constitute about half of the leucocytes. They are neutrophilic with a lobated nucleus. The granulocytopoiesis takes place in the intestinal myeloid tissue. The agranulocytes mainly include two cell types, termed spindle cells and lymphocyte-like cells. These cell types, however, transform into each other. Macrophages occur essentially in the peritoneal cavity rarely in the blood. Transition forms between macrophages and granulocytes may exist. The blood also contains cells which on morphological grounds have been termed thrombocytes. Whether these cells are identical with those necessary for clotting of the blood remains to be proved. With the exception of erythroblasts, the different lines of blast cells are difficult to identify and distinguish from each other. Possibly all lines of blood cells originate from agranulate lymphocyte-like stem cells, most of which are produced by the intestinal myeloid tissue.