1040 THE FEMALE ORGANS OF GENERATION. 



varies from fifteen to twenty : they are termed the tubuli lactiferi, or galactophori. 

 They converge toward the areola, beneath which they form dilatations, or ampullce, 

 which serve as reservoirs for the milk, and at the base of the nipple become 

 contracted and pursue a straight course to its summit, perforating it by separate 

 orifices considerably narrower than the ducts themselves. The ducts are composed 

 of areolar tissue, with longitudinal and transverse elastic fibres ; muscular fibres are 

 entirely absent ; their mucous lining is continuous, at the point of the nipple, witli 

 the integument. The epithelium of the mammary gland difiers according to the 

 state of activity of the organ. In the gland of a woman who is not pregnant or 

 suckling the alveoli are very small and solid, being filled with a mass of granular 

 polyhedral cells. During pregnancy the alveoli enlarge and the cells undergo 

 rapid multiplication. At the commencement of lactation the cells in the centre 

 of the alveolus undergo fatty degeneration, and are eliminated in the first milk 

 as colostrum-corpuscles. The peripheral cells of the alveolus remain, and form 

 a single layer of granular, short columnar cells, with a spherical nucleus, lining 

 the limiting membrana propria. These cells during the state of activity of the gland 

 are capable of forming, in their interior, oil-globules, which are then ejected into 

 the lumen of the alveolus and constitute the milk-globules. 



The fibrous tissue invests the entire surface of the breast, and sends down 

 septa between its lobes, connecting them together. 



The fatty tissue surrounds the surface of the gland and occupies the interval 

 between its lobes. It usually exists in considerable abundance, and determines 

 the form and size of the gland. There is no fat immediately beneath the areola 

 and nipple. 



Vessels and Nerves, The arteries supplying the mammae are derived from the 

 thoracic branches of the axillary, the intercostals, and internal mammary. The 

 veins describe an anastomotic circle round the base of the nipple, called by Haller 

 the circulus venosus. From this large branches transmit the blood to the 

 circumference of the gland and end in the axillary and internal mammary veins. 

 The lymphatics, for the most part, run along the lower border of the Pectoralis 

 major to the axillary glands ; some few, from the inner side of the breast, perforate 

 the intercostal spaces and empty themselves into the anterior mediastinal glands. 

 The nerves are derived from the anterior and lateral cutaneous nerves of the thorax. 



