RUTH RAND ATTERBURY 
426 
After the vascularization of the graft has become well de¬ 
veloped, changes may be observed in the scanty mesenchymal 
cells of the stroma. In typical development these cells form the 
connective tissue of the kidney. In the grafts they take a new 
line of differentiation, developing into small, scattered foci of 
granuloblastic tissue. 
The first signs of granuloblastic differentiation appear in 
grafts of six days’ growth. This process is illustrated by text 
Text figure E Camera-lucida drawing to illustrate granulopoiesis and various 
segments of urinary tubules. Metanephric graft of eight day’s growth. ci.H., 
ascending arm of Henle; B.C., Bowman’s capsule; c., capillary; d.H., descending 
arm of Henle; end., endothelium; e., erythrocyte; G., glomerulus; Gbl., granulo¬ 
blast; Get., granulocyte; N.T., convoluted tubules; U.T., collecting tubule. 
figure D, in which can be seen an early stage in the develop¬ 
ment of a granulopoietic focus. Several mesenchymal cells 
have apparently lost their syncytial arrangement and appear 
as free, hypertrophied, deeply basophilic, amoeboid cells. They 
exhibit all the characteristics of typical hemoblasts. A few of 
these cells already contain acidophilic granules in their cyto¬ 
plasm. In some the nucleus has become slightly polymorphic. 
