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a lobule of the epididymis (O.T. conus vasculosus). Within the head of the : epididymis the little canals finally open into the single much-convoluted tube which constitutes the chief bulk of the epididymis, and is called the duct of the epididymis. This canal, which is not less than 19 or 20 feet in length, may be said to begin in the head of the epididymis, and to end, after an extraordinarily tortuous course, at the tail by becoming the ductus deferens (Fig. 1006).
In most cases one or more slender convoluted diverticula from the duct of the epididymis may be found near its lower end. These receive the name of ductuli aberrantes, and one of them which is very constantly present often measures a foot or more in length.
Minute Structure. The duct of the epididymis and the efferent ductules are lined by a ciliated epithelium, the cilia of which maintain a constant current towards the ductus deferens. The duct of the epididymis possesses a muscular coat composed of an inner stratum of transversely and an outer stratum of longitudinally directed fibres. The wall, at first thin, becomes much thicker as the ductus epididymidis approaches the ductus deferens.
Duct of epididymis
FIG. 1007.-LEFT TESTIS AND EPIDIDYMIS VIEWED FROM BEHIND, showing the ductus epididymidis and the first part of the ductus deferens.
a long course, reaches the posterior border of the testis, where it breaks up into branches which enter the mediastinum testis, and are distributed along the septa and on the deep surface of the tunica albuginea.
The veins issuing from the posterior border of the testis form a dense plexus, called the plexus pampiniformis, which finally pours its blood through the spermatic vein, on the right side, into the inferior vena cava; on the left side the spermatic vein joins the left renal vein.
The nerves for the testis accompany the internal spermatic artery, and are derived through the aortic and renal plexuses from the tenth thoracic segment of the spinal medulla. The afferent fibres from the epididymis appear to reach the spinal medulla through the posterior roots of the eleventh and twelfth thoracic and first lumbar nerves. The arteries and nerves of the testis communicate with those on the lower part of the ductus deferens, namely, with the artery of the ductus deferens and with twigs from the hypogastric plexus.
The lymph-vessels of the testis pass upwards in the spermatic funiculus, and end in the lumbar lymph-glands.
The ductus deferens (O.T. vas deferens) is the direct continuation of the duct. of the epididymis. Beginning at the inferior extremity of the epididymis, it ends, after a course of nearly 18 inches, by opening as the ejaculatory duct into the prostatic or first part of the urethra. The duct in parts of its course is somewhat convoluted, and the actual distance traversed by it is not more than 12 inches. Placed in the first instance outside the abdominal cavity, the ductus deferens ascends
within the scrotum towards the lower part of the anterior abdominal wall, which it reaches not far from the median plane. During this part of its course the duct, together with the vessels and nerves of the testis, is surrounded by a number of loose coverings derived from certain layers of the abdominal wall, and the cord-like structure so formed is termed the funiculus spermaticus or spermatic cord. The ductus deferens, together with the accompanying vessels and nerves, now passes through the abdominal wall in an oblique passage, to which the name canalis inguinalis is applied. Within the abdomen the duct lies immediately beneath the peritoneum, and soon crossing over the pelvic brim, it enters the pelvis minor, on the side wall of which it proceeds backwards towards the base of the bladder. Here, near the median plane, the ductus deferens is joined by the duct of the correspondMedian umbilical ligament (urachus) Plica vesicalis transversa
External iliac vessels
Internal spermatic artery
External iliac artery
FIG. 1008.-VIEW OF THE MALE PELVIS SEEN FROM ABOVE AND BEHIND. The course
of the ductus deferens is well seen.
ing vesicula seminalis, and the ejaculatory duct, thus formed, having traversed the prostate, opens into the urethra.
At first the ductus deferens, like the canal from which it takes its origin, is very tortuous, but soon increasing in thickness, the duct becomes less twisted, and passes upwards along the medial side of the epididymis, behind the testis, to enter the spermatic funiculus (Fig. 1007). Its course is now almost vertically upwards towards the pubic tubercle, near which, crossing the medial part of the inguinal ligament [Pouparti], the duct enters the inguinal canal by the subcutaneous inguinal ring (Fig. 1017). Of the structures composing the funiculus spermaticus the duct is the most posterior, and it can be readily distinguished, even in the undissected subject, by its hard firm feel, when it is taken between the finger and thumb. In the inguinal canal the ductus deferens is directed laterally, upwards, and a little backwards to the abdominal inguinal ring, where, at a point half an inch above the inguinal ligament, and midway between the symphysis pubis and the anterior
superior iliac spine, it enters the abdomen. The distance between the point where the cord enters the inguinal canal to the point where it leaves it to enter the abdomen is about one and a half inches. While passing from the subcutaneous to the abdominal inguinal ring the ductus deferens, together with the other structures of the funiculus spermaticus, rests upon the upper grooved surface of the inguinal ligament, and is placed behind the aponeurosis of the external oblique and some of the lower fibres of the internal oblique muscle. From before backwards the duct rests, in the first instance, upon the falx aponeurotica or conjoined tendon of the internal oblique and transversus abdominis muscles, and farther laterally upon the fascia transversalis. Above the funiculus are some arching fibres of the internal oblique muscle which enter the falx. As the ductus deferens leaves the inguinal canal by the abdominal inguinal ring, it turns round the inferior
Ductus deferens Paravesical peritoneal fossa
FIG. 1009.-MEDIAN SECTION OF THE PELVIS IN AN ADULT MALE.
The coils of small intestine and colon which lay within the pelvis have been lifted out in order to give a view of the side wall of the pelvic cavity.
epigastric artery on its lateral and posterior aspect. Completely changing the direction of its course, the duct now runs for a short distance backwards, medially, and upwards, beneath the peritoneum, to a point one and a half to two inches from the pubic tubercle, where it crosses the ilio-pectineal line and enters the pelvis minor. In this part of its course the duct usually lies at first in front of the external iliac vessels, and then in the floor of a little triangular fossa, the trigonum femorale, between these vessels and the pelvic brim (Fig. 1009). On the side wall of the pelvis minor the ductus deferens is continued backwards, and a little downwards and medially, in the direction of the ischial spine, and lies immediately external to the peritoneum, through which it can usually be seen shining. In the pelvic part of its course the ductus deferens crosses on the medial side of (1) the obliterated part of the umbilical artery, (2) the obturator nerve and vessels, (3) the vesical vessels, and (4) the ureter (Fig. 1009).
Beyond the ureter the duct takes a somewhat sudden bend, and passes downwards and medially towards the median plane, beneath the peritoneum of the pelvic floor. Reaching the interval between the base of the bladder in front and the rectum behind, the ducts of opposite sides occupy the angle formed between the vesiculæ seminales (Fig. 1012). As they approach one another each duct becomes somewhat tortuous, sacculated, and dilated, and assumes a general resemblance in structure to a portion of the seminal vesicle. This dilated part of the ductus deferens is termed the ampulla ductus deferentis. As it turns medially the duct lies a short distance behind the ureter, and immediately in front of the free edge of the peritoneal fold (sacro-genital) which bounds the recto-vesical or recto-genital pouch of the peritoneum. Just above the base of the prostate the ductus deferens becomes once more a narrow canal, and in this position it is joined by the duct of the corresponding seminal vesicle to form the ductus ejaculatorius, which, after a short course downwards, forwards, and medially through the prostate, opens into the urethra.
In some cases the ductus deferens crosses the obliterated umbilical artery before it enters the cavity of the pelvis minor; it normally does so in the fœtus.
A and B. Drawings illustrating the seminal vesicle and the ampulla of the ductus deferens taken from tw different subjects.
C. The seminal vesicle and ductus deferens have been cut into to show the pitted structure of their walls.
Ductus Ejaculatorius (O.T. common ejaculatory duct).-The ejaculatory duct is a very slender canal, formed by the union of the ductus deferens with the duct of the corresponding seminal vesicle. It is less than one inch in length. and lies very close to its fellow of the opposite side as it passes through the prostate behind its median lobe. The ducts open by slit-like apertures into the first part of the urethra, one on each side of the utriculus prostaticus. They are well seen in sections through the upper part of the prostate (Fig. 1011).
The mucous membrane of the duct is thrown into numerous complicated folds, and it connexion with it are a number of remarkable minute diverticula, which are enclosed within the muscular coat of the duct.
Vesiculæ Seminales. The seminal vesicles are a pair of hollow sacculated structures placed in front of the rectum and behind the bladder (Fig. 1012). Each vesicle is usually about two inches in length, and has its long axis directed downwards, medially, and somewhat forwards. The superior extremity of the vesicle, which is partly covered by peritoneum, is large and rounded, and lies at a considerable distance from the median plane, behind the inferior end of the ureter The peritoneum of the recto-vesical or recto-genital pouch separates the upper end of the seminal vesicle from the rectum; below the peritoneal cavity the vesicle
Internal urethral orifice
and rectum are more intimately related. The vesicle tapers towards its inferior end, which is placed close to the median plane and immediately above the prostate. Inferiorly, the vesicle becomes constricted to form a short duct, the ductus excretorius, which joins the lateral side of the corresponding ductus deferens at an acute angle to form the ejaculatory duct. The medial side of each vesicle is related to the ductus deferens, and the lateral side, when the bladder is empty, lies close to the sloping pelvic floor. The seminal vesicle often assumes a more vertical
position when the bladder is FIG. 1011. distended; a more horizontal
direction when the bladder
is empty. Its superior end
THE RECTUM AND
URINARY BLADDER AT THE LEVEL AT WHICH THE URETERS
From a specimen in the Surgical Museum, Trinity College, Dublin.
is sometimes found to be curved backwards against the side of the rectum.
FIG. 1012.-DISSECTION TO DISPLAY THE POSTERIOR ASPECT OF THE VESICULE SEMINALES, THE AMPULLE OF THE DUCTUS DEFERENTES, AND THE PROSTATE. The coccyx and portions of the levatores ani have been removed, also a considerable portion of the rectum.
some cases the seminal vesicles are much smaller than usual, and may be less than one inch in length. Frequently they are asymmetrical as regards size and