136 



BIOLOGY OF THE LABORATORY MOUSE 



varies from three to seven. The number of efferent ducts in about 10 

 animals examined by us was three to five. The efferent ducts have two 

 parts: beginning at the testis, in the first part the ducts have a short, 

 straight, then convoluted course and are surrounded directly by the fat 

 body of the testis; in the second part the ducts are highly convoluted and 



Ductus epididymidis 



Capsule Efferent duct joining the ductus epididymidis Efferent duct 



Fig. 65. — Efferent duct joining the ductus epididymidis. (X200.) 



are surrounded by a connective tissue capsule which becomes continuous 

 with the capsule of the epididymis. The efferent ducts enter and form 

 the first small segment in the caput of the epididymis. Our own observa- 

 tions are in agreement with those of Benoit (6) and Young (98) who found 

 that the efferent ducts unite into a single duct which is in continuity with 

 the duct of the epididymis (Fig. 65). 



The lining of the efferent ducts is composed of alternating groups of 

 tall and low columnar epithelial cells, which give the lumen a characteristic 

 scalloped outline. The epithelial cells rest on a basement membrane. 



