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attached to the posterior border of the testis. Each border ends above in the superior extremity, and below in the inferior extremity of the testis. Owing to an obliquity of the long axis of the gland, the superior extremity of the testis lies on a more anterior and lateral plane than the inferior extremity.

Epididymis. The epididymis is a somewhat crescentic structure, which is curved. round the posterior border of the testis and overlaps to some extent the posterior part of the lateral surface of that organ. The superior, somewhat swollen part of the epididymis, is called the caput epididymidis or head, and overhangs the superior end of the testis, to which it is directly connected by numerous emerging ducts, by I connective tissue, and by the serous covering of the organ. The inferior and smaller end is termed the cauda epididymidis or tail, and is attached by loose areolar tissue and by the serous covering to the inferior end of the testis. The intermediate part, I the body, or corpus epididymidis, is applied against, but is separated from, the posterior part of the lateral surface of the testis by an involution of the serous covering of the organ, which forms an intervening pocket termed the sinus epididymidis (O.T. digital fossa).

The main mass of the epididymis is composed of an irregularly twisted canal, the ductus epididymidis, which forms the first part of the duct of the testis.

Minute sessile, or pedunculated, bodies are often found attached to the head of the epididymis or to the superior end of the testis. These are called appendices of the epididymis and testis (O.T. hydatids of Morgagni), and have a developmental interest. The minute body which lies on the superior end of the testis represents the free end of Müller's duct in the embryo and the fimbriated end of the uterine tube of the female; it is usually sessile. Above the head of the epididymis, and in front of the lower part of the spermatic cord, there may also be present a small rudimentary body called the paradidymis. This is rarely seen in the adult, and is best marked in young children.

Tunica Vaginalis.-The cavity within which the testis and epididymis are placed is lined by a smooth serous membrane-the tunica vaginalis-which resembles in appearance and structure the peritoneum, from which it is originally derived. The cavity is considerably larger than the contained structures, and extends not only down to a lower level than the testis, but also reaches upwards to a higher level than the gland. The sac, or cavity, tapers as it is traced upwards, and above the level of the testis the funiculus spermaticus or spermatic cord bulges forwards into its posterior part. The tunica vaginalis lines the cavity for the testis, and is reflected from the posterior wall of the scrotal chamber over the testis and epididymis, giving a covering to each. The part of the membrane lining the cavity is called the lamina parietalis or parietal portion of the tunica vaginalis, while the part clothing the testis and epididymis is termed the lamina visceralis or visceral portion. Between the lateral surface A part of the tunica vaginalis has been removed in order to show the ductuli efferentes and lobuli epididymidis. of the testis and the body of the epididymis, the visceral part of the tunica vaginalis dips in and lines a narrow interval called the sinus epididymidis (O.T. digital fossa). The entrance to the sinus is limited above and below by short crescentic folds of the tunica vaginalis, which pass from the testis to the head and tail of the epididymis. These folds are spoken of as the superior and inferior ligaments of the epididymis. In three positions the surface of the testis receives no covering from the tunica vaginalis-superiorly

FIG. 1004.-LEFT TESTIS AND EPIDIDYMIS.

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where the globus major is attached, inferiorly where the cauda epididymidis is in contact, and posteriorly where the blood-vessels and nerves enter the organ from the funiculus spermaticus or spermatic cord.

Tunica albuginea

Structure of the Testis and Epididymis.-Beneath the serous tunica vaginalis the testis is invested by an external coat, composed of dense white inelastic fibrous tissue called the tunica albuginea, from the deep surface of which a number of slender fibrous bands or septa dip into the gland. These the septula testis-imperfectly divide the organ into a number of wedge-shaped parts called lobuli testis (Fig. 1005). All the septa end posteriorly in a mass of fibrous tissue which is directly continuous with the tunica albuginea, and which projects forwards into the testis along its posterior border. This structure receives the name of mediastinum testis, or corpus Highmori, and is traversed by an exceedingly complicated network of fine canals, into which the minute tubules which compose the substance proper of the testis open. The mediastinum is also pierced by the arteries, veins, and lymph vessels of the testis. These vessels enter the posterior border of the organ, and traversing the mediastinum, spread out on the fibrous septa which radiate towards all parts of the deep surface of the tunica albuginea. In this way a delicate network of vessels (tunica vasculosa) is formed on the deep surface of the tunica albuginea and on the sides of the septa.

The mediastinum, the septa, and the tunica albuginea form a framework enclosing a number of imperfectly isolated spaces which are filled by a loosely packed substance of a light brown colour called the parenchyma testis.

Septula testis

Ductus deferens

Body of epididymis
Testicular artery Mediastinum testis
FIG. 1005.-TRANSVERSE SECTION OF THE
TESTIS AND EPIDIDYMIS.

The parenchyma is composed of enormous numbers of much-convoluted seminiferous tubules, called tubuli seminiferi contorti, and completely fills up the intervals between the septa. The minute tubules look like fine threads to the unaided eye, and are but loosely held together by a small amount of connective tissue. Usually three or four tubules are found in each lobule of the gland, and the total number in the testis has been estimated at about 600. The seminiferous tubules, after a course of about two feet in length, pass towards the mediastinum testis and unite at acute angles, to form a smaller number of slender tubes which run a straight course. These latter are called tubuli seminiferi recti, and open into a complicated network of fine canals situated in the substance of the mediastinum, called the rete testis. The tubules are much more twisted and convoluted in the cortical part of the gland, near the tunica vaginalis, than in the region of the mediastinum, and often give off side branches which, according to some observers, may effect anastomoses between the tubules. It appears doubtful, however, if the seminiferous tubules of the testis do really anastomose.

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Microscopic sections show that the walls of the seminiferous tubules are composed of a basement membrane and of an epithelial lining, formed of several layers of cells. Certain cells of this epithelium are, in the adult, constantly undergoing transformation into spermatozoa, and the appearance of the tubules in section varies much, according to age and to the greater or less activity of the epithelial cells.

The secretion of the seminiferous tubules is carried through the tubuli seminiferi recti into the rete testis, and leaves the latter, to reach the canal of the epididymis, through from fifteen to twenty minute tubules called ductuli efferentes testis or efferent ductules. These latter pierce the tunica albuginea and enter the caput epididymidis where it is in direct contact with the superior extremity of the testis. Each efferent ductule is at first straight, but soon becomes much convoluted, and forms a little conical mass of twisted tubule, called

te testis commu anery of the duc The lymph-v bar lymph-g

The ductus of the epididym after a course Prostatic or firs voluted, an Placed in the f

P a lobule of the epididymis (O.T. conus vasculosus). Within the head of the 1 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.

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Duct of epididymis.

v.e. Ductuli efferentes testis.

Duct of epididymis

FIG. 1007.-LEFT TESTIS AND EPIDIDYMIS VIEWED FROM BEHIND, showing the ductus epididymidis and the first part of the ductus deferens.

c.v. Lobuli of epididymis. v.r. Tubuli seminiferi recti.

r.v. Rete testis.

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.

DUCTUS DEFERENS.

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 correspond

Urinary bladder

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Internal spermatic artery

Ureter

External iliac artery
Hypogastric artery
Sacro-genital fold

Rectum

FIG. 1008.-VIEW OF THE MALE PELVIS SEEN FROM ABOVE AND BEHIND. The course
of the ductus deferens is well seen.

Obliterated umbilical artery
Inferior
epigastric artery

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

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THE DEFERENT DUCT.

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 While passing from the subcutaneous abdomen is about one and a half inches. 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 be of the internal oblique muscle which enter the falx. As the ductus deferens leaves

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the inguinal canal by the abdominal inguinal ring, it turns round the inferior

Branches of hypogastric artery Right ureter
Obturator artery

External iliac vessels

Inferior epigastric artery

Obliterated umbilical
artery (lig. umbilicale)

Plica vesicalis transversa
Vesical arteries

Nerve cord from hypogastric plexus

Sacro-genital fold

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.

Completely changing the epigastric artery on its lateral and posterior aspect. 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).

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