Study on the Blood Cells and Hemocytopoietic Tissues of the Hagfish, Eptatretus Burgeri. 2. Primitive Spleen

In the previous paper it was claimed that the peripheral blood is one of the hemocytopoietic tissue in itself (Tomonaga,1973). In this study the histological and cytological structure of hemocytopoietic tissues except peripheral blood was examined. Experimental animals were Japanese hagfish, Eptatretus burgeri. To study the distribution of the hemocytopoietic tissues in the hagfish serial sections of a whole body were made using a small hagfish of a body length of about 20 cm. On the one hand, sections of various organs of many hagfish of various body lengths from 15cm to 63cm were also examined. From these observations it was concluded that an active hemocytopoiesis was seen only in the submucosa of the intestine (primitive spleen) as described by Jorban and Speidel (1930). So, in this study various examinations including electron microscopic observations, autoradiography, X-ray irradiation were performed focusing on the primitive spleen.