GENITAL ORGANS OF THE COW 



605 



consistence than the fat which is found around and within the giand. It is enclosed 

 by a fibro-elastic capsule which sends inward numerous trabecule; these form the 

 interstitial tissue, and divide the gland into lobes and lobules. In the latter are 

 the secretory tubules and alveoli, which unite to form the larger ducts. Each lobe 

 has a duct, which opensat th&jJsase^pfj^yiSi^eatjnto a space called the lactiferous 

 sinus (Sinus lactiferiisX and" from this two (or three) lactiferous ducts (Ductus 

 lactiferi) pass through the extremity of the teat. These ducts are lined with a non- 

 glandular mucous membrane, which is covered with stratified squamous epithelium. 

 They are surrounded by unstriped muscular tissue, the bulk of the fibers being ar- 

 ranged in a circular manner to form a sphincter. 



The size and form of the mammary glands are subject to much variation. In the young 

 subject, before pregnancy, they are small and contain little gland tissue. During the latter part 

 of gestation, and especially during lactation, they increase greatly in size, and the gland tissue is 

 highly developed. After lactation the secretorj' structures undergo marked involution, and the 

 gland is much reduced in size. The relative amounts of gland sul^stance and interstitial tissue 

 vary greatly; in some cases a gland of considerable size contains little parench yjna and is con- 

 sequently functionally deficient. 



Vessels and Nerves. — The arteries are derived from the external pudic artery, 

 which enters the gland at the posterior part of its base. The veins form a plexus 

 on either side of the base of the gland, which is drained by the external pudic vein 

 chiefly. The lymph vessels are numerous and pass to the superficial inguinal and 

 lumbar lymph glands. The nerves are derived from the inguinal nerves and the 

 posterior mesenteric plexus of the sympathetic system. 



GENITAL ORGANS OF THE COW 



The ovaries of the cow are much smaller than those of the mare; they measure 

 usually about one and a half inches (ca. 3.5-4 cm.) in length, and an inch 



Fig. 534. — Ovaht of Cow. 

 1, Broad ligament of uterus; B, ligament of 

 ovary; 3, fimbria ovarica; 4. attachment of broad 

 ligament; 5, surface of ovary covered with ger- 

 minal epithelium; 6, corpora lutea; 7, Graafian 

 follicle. (From Leisering's Atlas.) 



Fig. 535. — Uterus of Cow, Contracted; Dorsal View. 

 a. Body of 'uterus; 6, b\ horn of uterus; c, ovary; d, d, 

 triangular folds connecting horns of uterus (Ligg. intercornu- 

 alia). (After Zieger.) 



(ca. 2.5 cm.) in thickness in their largest part; the weight is half an ounce 

 or more (ca. 15-20 gm.).^ They are oval in form, pointed at the uterine 

 1 Hess gives the following average measurements of the ovaries of 95 cows: Length of right, 

 4.3 cm.; of left, 3.71 cm.; width of right, 2.8 cm.; of left, 2.36 cm. Zieger found that the right 

 one was larger than the left in 65 out of 75 cases. 



