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against it, is depressed to form a little fossa termed the fossa ovarii, within which the ovary is placed. In the floor of this fossa are the obturator nerve and vessels The tubal extremity of the ovary lies below the level of the external iliac vessels, and its uterine extremity is placed just above the level of the peritoneum covering the pelvic floor. The fossa ovarii, in which the ovary lies, extends as far forwards as the obliterated umbilical artery, and backwards as far as the ureter and uterine vessels. Thus the mesovarian border of the ovary lies just behind the line of the obliterated umbilical artery, and the free border is on a plane anterior to the ureter (Fig. 1029). The medial surface of the ovary is almost completely covered by the uterine tube, which, passing upwards on it near its mesovarian border, arches over the tubal extremity, and then turns downwards in relation to the free border and posterior part of the medial surface (Fig. 1029).

In some cases the ovary is found to lie behind, or more rarely in front, of the fossa described above, and its long axis may be oblique instead of vertical. The above description, however, corresponds to the typical position of the organ in women who have not borne children. When

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FIG. 1030.-A, THE POSTERIOR ASPECT OF THE UTERUS AND BROAD LIGAMENT (the broad ligament has been spread out).

a, b, and c, the isthmus tube, the ligament of the ovary, and the round ligament of the right side eut short. B, DIAGRAMMATIC REPRESENTATION OF THE UTERINE CAVITY OPENED UP FROM ITS ANTERIOR ASPECT.

the uterus is much inclined towards the right side of the body the left ovary has its long axis directed obliquely downwards and medially, the right gland remaining vertical.

Connexions of the Ovary.-When the ovary is in position a small somewhat triangular peritoneal fold passes upwards from its tubal extremity, and becomes lost in the peritoneum covering the external iliac vessels and the psoas major muscle (Fig. 1028). This fold has received the name of ligamentum suspensorium ovarii, and is a portion of the superior and lateral part of the broad ligament of the uterus, which here contains between its two layers the ovarian vessels and nerves as they pass down into the pelvis to reach the hilum of the ovary. The vessels and nerves entering the ovary along its mesovarian border are enclosed in a sheath of peritoneum derived from the posterior layer of the broad ligament. In this way the ovary is connected along the whole length of its anterior border by a very short mesentery, or mesovarium, to the posterior aspect of the broad ligament (Fig. 1030). The uterine extremity of the ovary is connected with the lateral angle of the uterus by a ligament called the ligamentum ovarii proprium or ligament of the ovary. This has the form of a rounded cord enclosed between the peritoneal folds of the broad ligament, and is attached to the uterus, behind and below the point of entrance of the uterine tube. It is composed chiefly of smooth muscle fibres continuous with those of the uterus. The tubal extremity of the ovary is directly connected with one of the largest of the fimbriae surrounding the abdominal end of the uterine tube, which receives the name fimbria ovarica, or ovarian fimbria of the tube (Fig. 1030).

Descent of the Ovary.-Like the testes, the ovaries at first lie in the abdominal vity, and only later assume a lower position. At birth the ovary lies partly in the dominal, and partly in the pelvic cavity; soon, however, it takes up a position entirely ithin the pelvis minor. As in the male a gubernaculum is present in the early stages of evelopment. The ligament of the ovary represents the upper part of the gubernaculum

terus represents the inferior part, which is formed within the plica inguinalis (see p. 1295). t is a rare abnormality for the ovary, instead of entering the pelvis, to take a course similar o that of the testis, and pass through the inguinal canal into the tissue of the labium majus. Structure of the Ovary.-The ovary is for the most part composed of a connective issue, called the stroma ovarii, richly supplied by blood-vessels and nerves. The stroma contains very numerous spindle-shaped connective tissue fibres, and some elastic tissue. The surface of the ovary is covered by a layer of epithelium, which is composed of columnar cubical cells, and is continuous with the epithelium of the peritoneum forming the mesovarium. The ovarian epithelium is a persistent portion of the germinal epithelium of the embryo which covers the genital ridges, and from which the ova and other cells of the Graafian follicles are derived. The position in which it becomes continuous with the peritoneum can usually be distinguished as a fine white line near the hilum of the ovary. Shining through the epithelium of the fresh ovary (except

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FIG. 1031.-A. DIAGRAMMATIC REPRESENTATION OF THE MANNER IN WHICH THE FOLLICULI VESICULOSI
ARISE DURING THE DEVELOPMENT OF THE OVARY. B. DIAGRAM ILLUSTRATING THE STRUCTURE
OF A RIPE OR VESICULAR OVARIAN (GRAAFIAN) FOLLICLE.

in old age) are usually to be seen a variable number of small vesicles-the folliculi oöphori vesiculosi (O.T. Graafian follicles), in which the ovula, or ova, are contained. The number of follicles visible, and also the size which each follicle reaches before it ruptures and sheds its contents, is by no means constant. When a follicle ruptures and discharges the ovum its walls at first collapse, but later the cavity becomes filled with extravasated blood and cellular tissue of a yellowish colour. The resulting structure, called a corpus luteum, slowly degenerates unless impregnation has taken place, in which case it develops and becomes larger during pregnancy. As it atrophies the cells of the corpus luteum disappear, and the structure, losing its yellow colour, receives the name of corpus albicans. After a time the corpus albicans completely disappears. Owing to the periodic rupture of the folliculi vesiculosi, the surface of the ovary, which is at first smooth and even, becomes in old age dimpled and puckered.

A section through the ovary, especially in young children, presents in its superficial part a somewhat granular appearance, which is due to the presence of enormous numbers of small follicles, or collections of epithelial cells, embedded in the connective tissue near the surface of the ovary. The larger follicles lie deeper in the stroma, but when they become fully developed they pass towards the surface, where the ripe follicles are often seen slightly projecting and ready to burst. In the deepest part of the ovary the blood-vessels are most numerous, and here also some smooth muscle fibres are found.

The ova and the other cells that compose the folliculi vesiculosi are derived originally from the germinal epithelium which covers the developing ovary in the embryo. The epithelium, at first simple, grows down into the underlying tissue in the form of branching

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tube-like processes, or egg tubes." This takes place during foetal development, and the branching cellular processes so formed become broken up, within the stroma, into little nests or clumps of cells, each of which becomes a vesicular follicle. From the beginning some cells of the egg tubes are larger than the others; these become the future ova, while the cells round them become the investing cells of the follicle. The investing cells, at first flattened, form a single layer round each ovum. Later, becoming columnar, as the follicle increases in size and sinks more deeply in the stroma, these cells divide in such a manner that the ovum becomes surrounded by a double layer of cells. Fluid-liquor folliculi accumulates between the two cellular layers, except at one place where the inner cells surrounding the ovum remain attached to the outer layer or stratum granulosum. To the inner cellular mass enclosing the ovulum, or ovum, the term cumulus oöphorus (O.T. discus proligerus) is applied (Fig. 1031). The ripe follicle contains a relatively large amount of fluid, and the surrounding stroma becomes differentiated to form for it a theca folliculi, or capsule. This capsule is composed of an inner more vascular layer, the tunica interna, and an outer more fibrous layer, the tunica externa. There is reason to believe that in the human subject the formation of ova and follicles ceases before birth, and that the appearances which have led to the belief that they may originate during the first years of extra-uterine life have been due to pathological conditions. In the young child there are enormous numbers of small follicles in the superficial parts of the ovary, but in old age none are found in this situation.

The appearance and structure of the ripe ova are described on pp. 13-16.

Vessels and Nerves of the Ovary. The ovarian arteries, corresponding to the internal spermatic arteries of the male, are a pair of long slender vessels which spring from the anterior aspect of the aorta, below the level of origin of the renal vessels. Each gains the pelvis in the fold of peritoneum forming the suspensory ligament of the ovary, and enters the ovary at its mesovarian border, or hilum. The ovarian artery anastomoses freely, near the hilum, with other vessels, derived from the uterine arteries. The blood is returned by a series of communicating veins, similar to the plexus pampiniformis in the male.

The nerves of the ovary are derived chiefly from a plexus which accompanies the ovarian artery, and which is continuous above with the renal plexus. Other fibres are derived from the inferior part of the aortic plexus, and join the plexus on the ovarian artery (plexus arteria ovarica). The afferent impulses from the ovary reach the central nervous system through the posterior root fibres of the tenth thoracic nerve.

The lymph-vessels of the ovary join with those from the upper part of the uterus, and end in the lumbar lymph-glands.

TUBE UTERINE.

The uterine tubes (O.T. Fallopian tubes) are a pair of ducts or passages which convey the ova, discharged from the vesicular follicles of the ovaries, to the cavity of the uterus. Each tube is about four and a quarter inches in length, and opens at one end into the pelvic cavity near the ovary, and at the other end by a smaller opening into the lateral part of the uterine cavity. The tube is enclosed in a fold of peritoneum called the mesosalpinx, which is a portion of the broad ligament of the uterus.

The opening of the tube into the pelvic cavity-or ostium abdominale—is of small size, being only about 2 mm. in diameter when its walls are relaxed, and much narrower when the muscular coat of the tube is contracted. This opening is placed at the bottom of a funnel-like expansion of the tube called the infundibulum tubæ uterinæ, the margins of which are produced into a number of irregular processes or fimbriæ tubæ. The presence of these fimbria, many of which are branched or fringed, has given the name fimbriated extremity to this end of the uterine tube. The surface of the fimbria which looks into the cavity of the infundibulum is covered by a mucous membrane continuous with that lining the tube, while the outer surface is clothed by peritoneum. The mucous surfaces of the larger fimbria present ridges and grooves which are continued into the folds and furrows of the mucous coat of the tube. One of the fimbriæ, usually much larger than the rest, is connected either directly or indirectly with the tubal extremity of the ovary, and to it the name fimbria ovarica, or ovarian fimbria, is applied. The part of the tube continuous with the infundibulum, and into which the ostium abdominale leads, is called the ampulla tubæ uterinæ. This, the widest and longest portion of the uterine tube, is usually tortuous and of varying diameter, being in some places slightly constricted, and in others distended. The wide, thin-walled ampulla ends in the narrower, thicker-walled, and much shorter isthmus tubæ uterina

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which joins the lateral angle of the uterus. The last portion of the canal, or pars uterina, is embedded in the substance of the uterine wall, which it traverses to reach the cavity of the uterus (Fig. 1032, B). The opening into the uterus, or ostium uterinum tube, is smaller than the ostium abdominale, being about 1 mm. in diameter. The lumen of the canal gradually increases in width as it is traced outvards from the uterus towards the ovary.

Course of the Uterine Tube.-Traced from the lateral angle of the uterus the auterine tube is directed at first horizontally in a lateral direction towards the uterine extremity of the ovary. It then passes upwards in relation to the medial side of the mesovarian border of the ovary, until it reaches the tubal extremity, where, arching backwards, it descends along the posterior or free border, resting against the medial surface of the ovary (Fig. 1028). As the uterine tube describes this loop it often covers almost the entire medial surface of the ovary. The fimbriated end of the tube is applied against the free border and inferior part of the medial surface of the ovary, and from it the ovarian fimbria pass upwards to gain attachment to the tubal extremity of the gland.

The fimbriated end of the uterine tube lies in the abdominal cavity until the ovary in its descent has entered the pelvis.

Structure of the Uterine Tubes.-The wall of each tube, which is surrounded by a covering of peritoneum or tunica serosa, is composed of a number of concentric layers or coats. Immediately beneath the peritoneum is a layer of loose connective tissue, the tunica adventitia, in which lie many vessels and nerves. Beneath this is the tunica muscularis, composed of two strata of smooth muscle fibres-a more superficial thin stratum of longitudinally arranged fibres, the stratum longitudinale, and a deeper thicker layer, the fibres of which are circularly disposed, the stratum circulare. Deeper is a submucous layer or tela submucosa, and then the lining membrane or tunica mucosa. In the part of the tube near the uterus the muscular layer is thicker than towards the other end, and in the isthmus it forms the chief part of the wall. The mucous membrane, on the contrary, is thickest towards the fimbriated end, and here it forms the chief part of the tube wall. The stratum of circular muscle fibres is especially well developed near the uterus. The mucous membrane is thrown into numerous longitudinal folds, the plica tubariæ, which in the ampulla are exceedingly complex, the larger ones being beset on the surface by smaller folds. In transverse sections of this part of the tube the folds of the mucous membrane look like large branching processes projecting into, and almost completely filling up, the lumen of the tube. The mucous membrane is covered by a ciliated epithelium, the cilia of which tend to drive the contents of the tube towards the uterus. The epithelium is continuous with that of the uterus, and at the fimbriated end joins the peritoneum.

Vessels and Nerves of the Uterine Tube. The uterine tube receives its chief blood-supply from a ramus tubarius of the uterine artery, but it also receives small branches derived from the ovarian artery. The veins of the tube pour their blood partly into the uterine and partly into the ovarian veins. The lymph-vessels join the lumbar group of lymph-glands. The nerves are derived from the plexus that supplies the ovary, and also from the plexus in connexion with the uterus. The afferent fibres appear to belong to the eleventh and twelfth thoracic and the first lumbar nerves.

EP-OOPHORON AND PAR-OÖPHORON.

These are two rudimentary structures found between the layers of the broad ligament.

The ep-oöphoron (O.T. parovarium; often called the organ of Rosenmüller) lies in the mesosalpinx between the uterine tube and the ovary. In the adult it consists of a number of small rudimentary blind tubules lined by an epithelium. One of these tubules the ductus epoöphori longitudinalis (O.T. duct of Gärtner)-lies close to, and runs nearly parallel with, the uterine tube. It is joined by a number of the other tubules, or ductuli transversi, which enter it at right angles, from the neighbourhood of the ovary. The longitudinal duct is a persistent portion of the Wolffian duct, and represents the canal of the epididymis in the male, while the tubules which join it are derived from the mesonephros and represent the efferent ductules of the testis (and probably also the ductuli aberrantes of the duct of the epididymis). The ep-oöphoron is best seen when the part of the broad ligament in which it lies is held up to the light.

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One or more small pedunculated cystic structures, called appendices vesiculos: (O.T. hydatids of Morgagni), are often seen near the infundibulum of the uterine tube. These are supposed to represent portions of the upper end of the Wolffian duct.

The par-oöphoron is a collection of rudimentary tubules also enclosed by the layers of the mesosalpinx, but lying nearer the uterus than the ep-oophoron. These very rudimentary tubules represent the paradidymis in the male, and are derived from the part of the mesonephros which lies nearer the caudal end of the body of the embryo. Though sometimes visible in the child at birth, the paroöphoron in the adult can only be made out with the aid of a lens.

UTERUS.

The uterus, or womb, is a hollow, thick-walled, muscular organ placed within the pelvis between the bladder in front and the rectum behind. The ova discharged from the ovary enter the uterus through the uterine tubes, and, if fertilisation has taken place, undergo their development within it. In form the uterus is somewhat pear-shaped, the wide upper end of the organ projecting freely upwards and forwards into the pelvic cavity, while the lower more constricted part is connected with the vagina. The usual length of the adult uterus (when non-pregnant) is three inches, its greatest breadth is nearly two inches, and its maximum thickness is about one inch. In the description of the uterus we distinguish between an upper larger portion, somewhat flattened from before backwards, composed of fundus and body, and a lower more cylindrical part called the cervix (Fig. 1032).

The part of the uterus that lies above the level of a line joining the points of entrance of the uterine tubes is called the fundus uteri. The fundus is convex from before backwards and from side to side, its anterior and posterior aspects being directly continuous with the anterior and posterior surfaces of the body of the organ

The corpus uteri, when seen from in front or from behind, has a somewhat triangular outline, and lies below the fundus, with which it is continuous. The base of the triangle is directed upwards and is formed by a line joining the lateral angles of the uterus, or points of entrance of the uterine tubes; and the sides of the triangle correspond to the lateral borders of the uterus, which extend on each side from the lateral angle to the cervix. The margo lateralis or lateral border separates, on each side, the facies vesicalis (or anterior surface) from the facies intestinalis (or posterior surface) of the body. Both these surfaces are rounded, but the intestinal is much the more convex. The vesical surface rests against the upper aspect of the bladder, from which usually it is separated only by the layers of peritoneum forming the utero-vesical pouch. The intestinal surface forms the chief part of the anterior wall of the deep recess situated between the uterus and rectum, and is usually in contact with some part of the small intestine or the pelvic colon. The broad ligament passes laterally on each side of the uterus from the lateral border of the organ.

The cervix uteri is cylindrical, and at its commencement it is sometimes marked off from the body by a slight constriction. Its length is about one inch, and its inferior end, tapering somewhat, enters the upper part of the vagina. The cervix is attached to the margin of the opening in the vaginal wall, through which it passes, and in this way a portio supravaginalis is marked off from a portio vaginalis of the cervix. In the vaginal portion of the cervix there is an opening-the orificium externum uteri (O.T. external os uteri)-through which the cavity of the uterus communicates with that of the vagina. In a uterus which has not been pregnant this opening is nearly circular, but in women who have borne children it is usually a transverse slit with a somewhat irregular outline. In front of, and behind, this opening the cervix forms two lips, an anterior and a posterior, the labium anterius and the labium posterius. The anterior lip is thicker, and slightly more rounded; it is placed upon a lower level than the posterior lip, which is slightly longer and thinner. The cervix enters the vagina through the upper part of its anterior wall in such a manner that the external orifice of the uterus is directed backwards and downwards against the upper part of the posterior vaginal wall (Fig. 1033).

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