Part 162

The figure represents a cotyledon of medium size. (After Ellenberger, in Leisering’s Atlas.) ]

FIG. 414.—GENITAL ORGANS OF COW, DORSAL VIEW.

The right uterine cornu and the vagina and vulva are opened up: 1, Labium vulvæ; 2, ventral commissure; 3, glans clitoridis; 4, glandula vestibularis major, exposed by slit in mucous membrane; 5, opening of duct of preceding; 6, suburethral diverticulum; 7, external urethral opening; 8, openings of canals of Gartner; 9, os uteri; 10, corpus uteri; 11, cornu uteri; 12, cotyledons; 13, Fallopian tube; 14, ostium abdominale tubæ; 15, ovary (From Leisering’s Atlas, reduced.) ]

The =broad ligaments= are not attached in the sublumbar region as in the mare, but to the upper part of the flanks, about a handbreadth below the level of the external angle of the ilium. They contain a conspicuous amount of unstriped muscle. The =round ligaments= are well developed, and can be traced distinctly to the vicinity of the internal inguinal ring.

The =vagina= is somewhat longer and more roomy than that of the mare; its wall is also thicker. Its average length in the non-pregnant animal is about eight inches (ca. 20 cm.); but in the pregnant cow the length increases to twelve inches (30 cm.) or more. The recto-genital pouch of peritoneum extends backward about five inches (ca. 12 cm.) on the dorsal surface, while ventrally the serous coat only extends backward about two inches (ca. 5 cm.).

This gives ample space dorsally for the incision of the fornix vaginæ in oöphorectomy.

In the ventral wall of the vagina, between the muscular and mucous coats, there are frequently present the two =canals of Gartner= (Ductus epoöphori longitudinales). When well developed they may attain the diameter of a goose quill, and may be traced forward to the anterior part of the vagina or even further. They open posteriorly near the external urethral orifice.

These tubes are remnants of the Wolffian ducts, and, like other fœtal vestiges, are very variable. Röder states that the right canal was absent in over 52 per cent., the left in only 22 per cent., of the cows examined by him. In some cases they may be traced in the broad ligaments for a variable distance toward the ovary. They are of clinical interest in that cysts frequently form along their course.

FIG. 415.—DIAGRAMMATIC SAGITTAL SECTION OF PART OF UROGENITAL TRACT OF COW, SHOWING SUBURETHRAL DIVERTICULUM. ]

The =vulva= has thick wrinkled labia, and both commissures are acute; the lower one is pointed, and has on it a number of long hairs; it lies about two inches (5 cm.) behind, and about the same distance below, the level of the ischial arch. The =glans clitoridis= is small; the =crura= are about four inches (ca. 10 cm.) long and are flexuous. The =external urethral orifice= or meatus urinarius is four or five inches (10 to 12 cm.) from the ventral commissure. Beneath it is a blind pouch, the =suburethral diverticulum=, which is more than an inch (ca. 3 to 4 cm.) long, and readily admits the end of a finger.

The form and position of this pouch should be carefully noted on account of the difficulty it causes in catheterizing the bladder. If the catheter is passed along the ventral wall of the vulva (as in the mare), it will always enter the pouch instead of the urethra.

The =glandulæ vestibulares majores= (or glands of Bartholin) are situated on the lateral walls of the vulva, under the constrictor vulvæ. They are little over an inch (ca. 3 cm.) long and about half an inch (ca. 1.5 cm.) in width. Each has a single duct which opens about an inch and a half (ca. 3 to 4 cm.) lateral to and behind the external urethral orifice.

The =urethra= of the cow is about four inches (10 cm.) in length; it is narrower and much less dilatable than that of the mare. It is fused dorsally with the wall of the vagina, while laterally and ventrally it is covered by the constrictor vaginæ muscle.

The =mammary glands=, normally two in number, are popularly termed the udder. They are very much larger than in the mare, and the body of each is somewhat ellipsoidal in form, but flattened transversely. The =base= (or dorsal surface) of each gland is slightly concave and slopes obliquely downward and forward in adaptation to the abdominal wall, to which it is adherent; posteriorly it is in relation to the large supramammary lymph glands and a quantity of fat. The inner surface is flat, and is separated from the other gland by a well-developed double septum. The outer surface is convex. Four well-developed teats are present; they average about three inches (ca. 7 to 8 cm.) in length. It is customary to consider the udder to consist of four “quarters.” There is no septum nor visible division between the two quarters of the same side, but, on the other hand, injections of fluids of different colors into the two teats of the gland demonstrate that the cavities drained by them do not communicate.

FIG. 416.—CROSS-SECTION OF MAMMARY GLANDS OF COW.

a, Body of gland; b, lactiferous sinus; c, cavity of teat; d, duct of teat; e, intermammary groove; f, septum between glands; g, supramammary fat. ]

The size and form of the glands vary greatly; in the highly specialized dairy breeds (e. g., Holsteins) they often attain enormous dimensions. The size of the udder is not a certain index of its productivity, since some so-called “fleshy” udders contain a very large amount of interstitial tissue and relatively little parenchyma. Small accessory teats often occur posteriorly; commonly these are rudimentary and imperforate (polythelia), but sometimes they drain a small amount of gland substance (polymastia). Sanson described a case in which there were seven teats, all giving milk.

Each teat has a single duct which widens superiorly and opens freely into a roomy =lactiferous sinus= or milk cistern (Sinus lactiferus). The =lactiferous duct= or teat canal is lined by a glandless mucous membrane which is covered with stratified squamous epithelium; the lower part (ca. 1 cm.) of the canal is narrow, and is closed by a =sphincter= of unstriped muscle. The =mucous membrane= of the sinus forms numerous folds which render the cavity multilocular.

=Vessels and Nerves.=—The blood-supply is derived from the =external pudic arteries=. The =veins= form a circle at the base of the udder, from which the blood is drained by three trunks, viz., the very large =subcutaneous abdominal= (“milk vein”), the =external pudic=, and the =perineal vein=. The =lymphatics= are numerous, and pass to the supramammary glands chiefly. The nerves are derived from the =inguinal nerves= and the =posterior mesenteric plexus= of the sympathetic.

GENITAL ORGANS OF THE SOW

FIG. 417.—GENITAL ORGANS OF SOW, DORSAL VIEW. THE VAGINA AND CERVIX UTERI ARE SLIT OPEN.

1, Labia vulvæ; 2, glans clitoridis; 3, vulva; 4, external urethral orifice; 5, vagina; 5′, cervix uteri; 6, corpus uteri; 7, cornua uteri, one of which is opened at 7′ to show folds of mucous membrane; 8, Fallopian tube; 8′, abdominal opening of tube; 9, ovaries; 10, ovarian bursa; 11, broad ligaments of uterus; 12, urinary bladder. (From Leisering’s Atlas.) ]

The =ovaries= are concealed in the bursa ovarii, owing to the large extent of the mesosalpinx. They are more rounded than in the bitch, and have a distinct hilus. They are situated usually as in the cow, but their position is quite variable in animals which have borne young. The surface commonly presents rounded prominences, so that sometimes the gland has an irregular, mulberry-like aspect; this is due to the fact that there is very little stroma and the larger Graafian follicles project from the surface.

The =Fallopian= or =uterine tubes= are long (ca. 15 to 30 cm.), and less flexuous than in the mare. The fimbriated extremity forms an ampulla and has a large abdominal opening. The uterine end shades insensibly into the small extremity of the cornu of the uterus.

The =uterus= presents several striking features. The =body= is only about two inches (ca. 5 cm.) long. The =horns= are extremely long and flexuous, and are freely movable, on account of the large extent of the broad ligaments. The extremities of the horns taper to about the diameter of the Fallopian tubes. The =neck= is remarkable for its length (ca. 15 to 20 cm.) and the fact that it is directly continued by the vagina without forming any intravaginal projection (os uteri). It can be distinguished by the transverse folds of its mucous membrane and the thickness of its wall.

The changes in form and position of the uterus during pregnancy are similar to those mentioned later in the case of the bitch.

The =vagina= is about four or five inches (ca. 10 to 12 cm.) long in a sow of medium size. It is small in caliber, and has a thick muscular coat which consists mainly of circular fibers. The mucous membrane is plicated, and is intimately united with the muscular coat.

The =vulva= is relatively long. The inferior commissure is pointed and dependent. The mucous lining is plicated. There is a small =suburethral diverticulum=. The vestibular glands are small and variable in number. The vestibular bulbs are little developed. The canals of Gartner may sometimes be traced as far as the ovary, but are often difficult to find.