DISEASES OF THE MAMMARY GRAND. 
439 
Malignant tumours of the uterus are rare in all domesticated animals, 
and are still more rarely diagnosed. Where, for reasons of sentiment, 
the owner attaches unusual importance to the animal’s preservation, 
ablation of the uterus may be performed, but the operation is only 
practicable in small animals. 
Atresia of the neck of the uterus or closure of the os sometimes renders 
animals sterile and calls for operation. The entrance to the uterus can 
usually be dilated by introducing the fingers or a sponge tent. 
V.—DISEASES OF THE MAMMARY GLAND. 
The mammary gland consists of parenchymatous tissue and stroma. The 
formation of the former is partly alveolar, partly tubular. In the connective 
tissue of the stroma lie variously-shaped spaces, lined by a membrana propria, 
which (like the alveoli of the lung in the smallest bronchi) open by gland ducts. 
Both are lined with low cylindrical epithelium, and together form the milk- 
secreting tissue. The milk flows thence into the milk ducts, to pass either 
directly outwards through the teat (man and carnivora), or in herbivora, into 
a large cavity at the base of the teat, termed the galactophorous sinus. The 
ruminant’s udder possesses only one galactophorous sinus and teat for each 
division ; in the mare’s udder every teat is supplied by two sinuses. From 
the galactophorous sinus a narrow canal, lined with mucous membrane, leads 
to the outer air, and in mares two of these, therefore, exist in every teat, in 
ruminants only one. In swine, each teat may sometimes have two delivery 
ducts. In herbivora, then, each teat corresponds to a particular division of 
the udder ; in cows, to a quarter; in sheep and goats, to one-half of the 
udder. In carnivora the divisions of the udder are, externally, not so sharply 
bounded, and each is connected with the eight to twelve openings on its 
corresponding teat. 
The stroma consists of connective tissue and elastic fibres, which form a 
capsule under the skin, and surround the udder. From this capsule the 
stroma is continued inwards into the gland, filling the space between the 
alveoli and ducts of the gland, and is analogous to the interstitial connective 
tissue of the lungs. The quantity of stroma varies. During lactation it 
diminishes, and in place of it alveoli develop. In the udder of young animals, 
connective tissue predominates. Between the larger divisions of the gland 
and their ducts lie considerable masses of connective tissue, which often 
contain elastic fibres and fat. 
A double system of lymph vessels exists in the udder; the one lying near 
the surface arises from the capsule, and is connected with the lymph vessels 
of the skin ; the other invests the alveoli, which are surrounded by fine lymph 
vessels. Furstenberg distinguished between the surface lymph vessels arising 
close under the skin of the udder, which pass into the depths along with the 
chief veins, and those which arise from the plexus in the interior of the gland, 
and accompany the deeper-lying venous branches. Furstenberg states that 
during lactation the lymph vessels appear to be distended with lymph. He 
also succeeded in filling them with air from the milk ducts, and discovered a 
valvular arrangement in them. 
The alveoli are directly surrounded by lymph capillaries, which in their turn 
are surrounded by capillary blood-vessels ; according to Rauber these lie partly 
in the lymph spaces, into which they pour fluid contents and leucocytes, 
