John Bruce MacCalluni 



249 



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Fig. i. Transverse section of Wolffian body 

 of human embryo LXXVI, (V. B. 4.8). The 



of this embryo. The Malpighian bodies are not fully formed. 

 A crescent-shaped bending of the end of the tubule is present with 

 the concave side thickened, and the opposite side thinned out to a 

 layer of flat cells. A small mass of capillaries is pushed into the 

 concave side of this end structure, 

 as shown in Fig. 4. The tubule 

 is curved like the letter S. The 

 lining epithelium of the Wolffian 

 duct is not different in any essen- 

 tials from that of the tubules. 



An older human embryo, II (V. 

 B. 3, N. B. 7, probable age 4 

 weeks), shows a slight advance on 

 this last stage. In the Wolffian 

 body there are 30 tubules and 30 

 glomeruli. These correspond 



throughout with the greatest ac- 

 curacy. There is no trace of the 

 short anterior duct described in 

 the preceding embryos. The 



Wolffian tubules are" S-shaped, Mau^'^wan corpuscle is she Vn i^ 

 with a slight dilatation near the 



Malpighian body. Except for this there is no differentiation into a secret- 

 ing and a conducting region. In an embryo, CLXIII (V. B. 9, F. B. 9, 

 probable age 4^ weeks), this differentiation is well marked. The duct 

 itself is lined by regularly arranged cells. The tubules near the duct 

 possess a small lumen and are lined by small polygonal cells. In the 

 region of the Malpighian body the lumen becomes considerably wider, 

 and the cells lining the tubule are large and rich in protoplasm. This 

 difference, which was first noticed by J. Mliller, is seen in a human 

 embryo about 5 weeks old, CIX (V. B. 11, N". B. 10.5). In embryo 

 CXLIV (V. B. 14, K B. 12, probable age 5^ weeks), the Wolffian body 

 possesses 27 tubules and approximately 25 glomeruli. Figure 5 is a 

 longitudinal section of the Wolffian body taken from a sagittal series 

 of the embryo, showing the relation of the organ to the testis and 

 kidney. The close relation between the Wolffian body and the testis 

 in which tubules are just beginning to develop, must be noted. That 

 these tubules become connected with the Wolffian body tubules through 

 the Malpighian bodies, and that their subsequent connection with the 

 epididymis is thus established will be shown later. In this embryo the 

 Miillerian duct can be seen only as a very short tube extending back- 



