_Vas deferens._—The vas deferens runs down the posterior wall of the epididymis and turns upwards to enter the abdominal cavity through the inguinal canal. It then runs between bladder and rectum to end as the ductus ejaculatorius. Before the vas deferens receives the duct of the seminal vesicle it forms a spindle-like enlargement, the so-called ampulla. The vas deferens opens under the name of ductus ejaculatorius into the prostatic urethra. The length of the vas deferens is about 60 centimeters, its diameter is about 3 millimeters. The wall of the vas deferens is very thick, giving on palpation the feeling of a piece of rope. It is lined inside with a light cylindrical epithelium which rests upon a layer of fibrous connective tissue. This fibrous substratum is surrounded by a thick, muscular coat of non-striated fibres. The muscular coat is composed of two longitudinal layers, which include between them a circular layer. The muscular coat is surrounded by a layer of connective tissue, the so-called adventitia. _Spermatic cord._—In its course from the testicle to the internal ring of the inguinal canal the vas deferens is accompanied by the arteria and vena spermaticae internae. The three organs form the spermatic cord. But although the three organs are intimately connected, still the vas deferens is recognizable without difficulty by its rope-like consistency and is easily severed, as in the operation for the sterilization of the male. The vein forms a tendril-like tress-work, which is called the plexus pampiniformis. In pathological conditions the plexus forms the varicocele. _Seminal vesicles._—The seminal vesicles may be considered as diverticles of the vasa deferentia. The vesicles are lying in the sulcus, between the prostate and the bladder, and extend obliquely outward and backward. The length of the seminal vesicles is about 8 centimeters, their diameter is about 7 millimeters. The vesicles form a bulbous mass of convoluted tubes. Being a derivative from the vas deferens, the wall of the tubes consists of the same strata as the vas deferens, i. e., of an adventitia followed by the muscular coat, then by the fibrous substratum, and finally by a layer of cylindrical epithelia. The mucous membrane possesses numerous tubulous glands. In this way the vesicles serve not only as reservoirs for the sperma, but may be considered as veritable glands. By the junction of the pointed ends of the seminal vesicles with the vasa deferentia, the ejaculatory ducts are formed. [Illustration: CUT VII. _Male genital apparatus, side view. After Zucherkandel and Testut._ b, bladder; p, al, ml, the three lobes of the prostatic gland; u, ureter; sv, seminal vesicle; vd, vas deferens; ed, ejaculatory duct.]