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 trabeculze; 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 opens at the base of the teat into a space called the lactiferous 
sinus (Sinus lactiferus), 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 im size, and the gland tissue is 
highly developed. After lactation the secretory structures undergo marked involution, and the 
gland is much reduced in size. The relative amounts of gland substance and interstitial tissue 
vary greatly; in some cases a gland of considerable size contains little parenchyma 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 
Fic. 534.—Ovary or Cow. Fic. 535.—Urervus oF Cow, Contractep; Dorsat View. 
1, Broad ligament of uterus; 2, ligament of a, Body of uterus; 5, 6’, horn of uterus; c, ovary; d, d, 
ovary; 3, fimbria ovarica; 4, attachment of broad triangular folds connecting horns of uterus (Ligg. intercornu- 
ligament; 5, surface of ovary covered with ger- alia). (After Zieger.) 
minal epithelium; 6, corpora lutea; 7, Graafian 
follicle. (From Leisering’s Atlas.) 
(ca. 2.5 em.) 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, 
43 em.; of left, 3.71 cm.; width of right, 2.8 cm.; of left, 2.36 cm. Zieger found that the nght 
one was larger than the left in 65 out of 75 cases. 
