GENITAL ORGANS OF THE EWE 609 



cm.) long and is fiexuous. Only the pointed end of the glans is visible in the ventral 

 commissure of the vulva. 



The urethra. 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 vaginae 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 of each gland 

 is slightly concave and slopes obliquely downward and forward in adaptation to 

 the abdominal wall, to which it is adherent; it is in relation posteriorly to the large 

 supramammary lymph-glands and a quantity of fat. The medial surface is flat, 

 and is separated from the other gland by a well-developed double septum. The 

 lateral surface is convex. Four well-developed teats are present; they average 

 about three inches (ca. 7-8 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. 



The size and form of the glands vary greatly; in the highly specialized dairy breeds (e. g., 

 Holsteins) they often attain enormous dimensions. Tlie size of the udder is not a certain index 

 of its productivity, since some so-called "fleshy" udders contain a very large amount of inter- 

 stitial 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 superiorlj^ and opens freely into a 

 roomy lactiferous sinus (Sinus lactiferus), popularly known as the milk cistern. 

 The lactiferous duct (Ductus lactiferus) 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 arteries are 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, the external pudic, and 

 the perineal vein. The lymph vessels 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 EWE 



The genital organs of the ewe resemble in general those of the cow, but a fev/ 

 special features may be noted. . 



The ovaries are almond shaped and are half an inch or more (ca. 1.5 cm.) m 

 length. 



There is no demarcation between the uterine tube and the horn of the uterus; 

 the tube is very fiexuous near the infundibulum. 



The uterus resembles that of the cow. The horns are four or five inches (ca. 

 10-12 cm.) long and taper in such a manner to their junction with the uterine tubes 

 that no clear distinction between the two exists. They are coiled in a close spiral, 

 and an inch or more of their posterior parts are united. The body is less than an 

 mch (ca. 2 cm.) long. The cotyledons are much smaller than those of the cow and 

 39 



