70 THE STRUCTURE OF THE FOWL 



The seminiferous tubules join ducts which 

 carry the spermatozoa into those numerous 

 convohited tubes which compose the epi- 

 didymis and finally unite to form the deferent 

 duct. 



Microscopically the deferent duct has a 

 wall formed by fibrous and muscular tissue 

 and lined by columnar epithelium (Fig. 38). 

 The duct contains no glands. 



The reproductive organs of the hen are 

 remarkable in that, though provision is made 

 in the embryo for two ovaries and two oviducts, 

 only the left ovary and its duct reach maturity. 



The single ovary (Figs. 12 and 39) hes partly 

 cranial and partly ventral to the left kidney, 

 and consists of a mass of loosely -connected, 

 yellowish, vascular and rounded objects each con- 

 taining an ovum. The size of the bodies varies 

 widely, dependent upon the stage of develop- 

 ment of the contained ovum. In an ovary ex- 

 amined during the egg-laying period some of the 

 vesicles will be of considerable dimensions ; 

 while during the resting-stage they will all be 

 small. Microscopic examination shows that 

 each ovum is surrounded by a granular mem- 

 brane {membrana granulosa) composed of epi- 

 thelial cells, whose duty is doubtless to act as 



