32 



OBSTETRICAL AuVATOMV. 



organs of generation. They are the glands destined to secrete the fluid — . 

 milk — which is to nourish the young animal for some time after birth. 

 In early life they are rudimentary, but become developed with age, and 

 attain their full dimensions when the female is capable of reproduction ; 

 and especially at the full period of gestation, when their function is about 

 to be carried on actively. After parturition their largest development is 

 reached, and when the )''oung creature has completed its term of sucking, 

 they lose their activity and diminish considerably in size. In the Mare 

 they are two in number, placed beside each other in the inguinal region, 

 about nine inches in front of the vulva, where they take the place of the 

 scrotum in the male. Externally, they appear as two hemispherical 

 masses separated by a shallow furrow ; each has in its centre, on each 

 side of the mesian line, a conical, slightly flattened prolongation named 

 the feaf or nipple^ which is perforated by several orifices from which the 

 milk escapes, and by which the young creature obtains that fluid by 

 suction. The two glands are retained in their position by the fine skin 

 covering them, and which, destitute of hair at the extremity of the teats, 

 though elsewhere provided with a soft short down, is smooth, pliable, and 

 unctuous from the presence of sebiparous follicles. At the base of the 

 teat are a number of small tubercles, which correspond to the areola of 

 the nipple in woman ; these are the glands. 



The mammae are also attached to the abdominal tunic by means of 

 several wide, short, but elastic bands, which bear some analogy to the 

 suspensory ligaments of the prepuce in the male. 



In STRUCTURE each udder offers an envelope of yellow elastic fibrous 

 tissue^ glandular tissue^ the sinuses or galactophorous reservoirs^ and the 

 lactiferous ducts ^ with excretory canals or niilk ducts. 



The elastic envelope, joined at the mesian line with that of the opposite 

 udder, is strengthened by wide bands detached from the tunica ahdominalis ; 

 it furnishes from its internal face numerous prolongations which, crossing 

 each other in the mass of the gland, form septa or partitions that divide 

 it into distinct lobes and lobules, which are in this way somewhat indepen- 

 dent of each other ; so that one or more may be diseased or deranged in 

 function, without the others being involved. Externally, this envelope is 

 closely adherent to the skin, through the medium of a dense layer of con- 

 nective tissue. 



The glandular tissue offers the same arrangement as other conglomerate 

 glands, and is composed of acini or caecal vesicles clustered, like grapes 

 on their stalk, around the tubuli lactiferi, or ultimate terminations of the 

 excretory ducts. These, co#imencing by cul-de-sac extremities, open into 

 one another to form dilatations {ampullce), and finally converge into a 

 number of principal canals, which end in the galactophorous sinuses 

 {sinus lactei). The acini of the lobules, as well as the ducts, are lined by 

 polyhedral epithelium ; this becomes spherical and infiltrated with fat 

 during lactation. 



The galactophorous sinuses or reservoirs are situated slightly above the 

 base of the teat, and are generally two in number — one in front, the other 

 behind ; though there are sometimes three, and even four. They nearly 

 always communicate with each other, and are prolonged into the teat by 

 a corresponding number of terminal and independent excretory canals, 

 whose orifices are always very narrow, and are seen at the free extremity 

 of that body, which is obtuse and rounded. Collectively, these excretory 

 canals are much wider at the base of the teat than at the extremity ; the 



