MALE REPRODUCTIVE SYSTEM OF MAMMALS 



243 



faces of the testes and somewhat \eiitrally and dorsally as the tunica 

 vaginahs visceralis. Between these two tunics is a very loose fibro- 

 elastic connective tissue and fluid, making possible a free movenuMit 

 of the testis within the scrotum. AVithin the tunic vaginalis, a 

 connective-tissue sheath, the tunica albuginea, extends perforated 

 partitions, or septa, into the testis and forms compartments or 

 lobules containing the seminiferous tubules. A mid-posterior region 

 of this tissue located toward the surface of the testis is very vascular 

 and called the mcdiastimmi. The lobules so set off in the testis 



Fig. 149. — Photograph of a cross-section of a seminiferous tubule of the woodchuck 

 showing interstitial tissue between it and adjacent tubules. 



contain from several to many convoluted seminiferous tubules. 

 (Fig. 149.) As the tubules approach the mediastinum they unite 

 to form less-coiled tubules until a few much smaller straight tubules 

 are formed which connect within the mediastinum into a network 

 of small ducts called the rete testis. From the upper region of the 

 rete testis a number of larger tubules compose the vasa efferentia, 

 which are at first straight but become twisted and increase in diam- 

 eter as they pass toward the upper posterior region of the testis. 

 These join to form the epididymis, a much-coiled duct forming a 

 mass divided into a head and tail portion at either end of the testis, 

 and the body of the e]Mdidymis along the central portion. The 

 tail portion of the epididymis straightens out to become the vas 



