Granulopoiesis in tadpoles of Rana esculenta. Survey of the organs involved.

The topography and nature of granulopoietic tissues appearing during the larval period of Rana esculenta have been investigated using light and electron microscopy. The formation of eosinophils and heterophils occurred in the interstices of the pronephros and opisthonephros, in the mesenchymal sheath surrounding the pronephric duct, as well as in the mesentery and mesenchymal coat of the bile duct and hepatic ducts. Developing basophils were very rare, being detectable only in the stroma of the trunk kidneys. The pronephric interstices additionally contained differentiating lymphocytes, the opisthonephric interstices differentiating lymphocytes and erythrocytes. In contrast, the mesenchymal sheath of the pronephric duct as well as the mesentery and the mesenchymatous coat of the bile duct and hepatic ducts were solely granulopoietic.