662 SPECIAL HISTOLOGY. 



muscular fibres, and nothing but a nucleated, longitudinally fibrous, 

 connective tissue with fine elastic fibres. Henle, however, more 

 recently, thinks that he has noticed longitudinal muscles in the lacteal 

 ducts, not those of the nipple, but more deeply within the gland. 



The nipple (mamilla) and the areola, present numerous smooth mus- 

 cles, to which the contractility of those parts is owing (vid. 34) ; a 

 delicate cuticle, the horny layer of which, in the female, is not more than 

 0*006 of a line thick, whilst the Malpighian layer has a thickness of 0'04 

 of a line and is colored in the deeper portion ; and compound papillae. 

 1-10-1-33 of a line long. On the breast itself, the papillce are small 

 (1-60-1-80 of a line) and simple, and the epidermis still finer (0-032- 

 0*04 of a line), although with a thicker horny layer of 0-02-0-024 of a 

 line. In the areola, especially at its borders, but not on the nipple 

 itself, there are large sudoriparous glands, often with peculiar contents, 

 and large sebaceous follicles with fine hairs, which frequently form 

 little papillce, visible on the exterior (vid. 68 and 73). In the male, 

 I have seen sebaceous glands without hairs, also on the nipple. 



The bloodvessels of the lacteal glands are numerous, and surround the 

 gland-vesicles with a rather close plexus of capillaries. The veins in 

 the areola constitute a circle, which is not always quite complete (circu- 

 lus venosus Halleri). The lymphatics are equally abundant in the skin 

 covering the gland, whilst in the gland itself they have not yet been 

 demonstrated. The nerves of the skin covering the mamma are derived 

 from the supraclavicular nerves, and the cutaneous branches of the 

 second, third, and fourth intercostals. In the interior of the gland, no 

 other nerves can be traced than a few fine twigs accompanying the 

 vessels, whose termination is unknown. 



At the time of lactation the gland enlarges very considerably. Its 

 tissue is no longer uniform, whitish, and firm, but softer, granular, and 

 lobate, with a yellowish-red, glandular parenchyma, distinctly bounded 

 by the whitish, spongy interstitial tissue. The gland-vesicles and lacti- 

 ferous ducts are wider, filled with milk, and the vessels excessively 

 multiplied. In the external parts, the enlargement of the areola and 

 of the nipple is especially worthy of remark ; the cause of which appears 

 to depend upon a growth of these parts, with all their elements, includ- 

 ing the muscular fibres and minute glands ; arid not in a simple exten- 

 sion of the color over a larger surface. In the male, the lacteal gland 

 is quite rudimentary j 2 inches broad, and 1-3 lines thick, not lobed, 

 and firm. The lacteal ducts have no sinuses, and are never so far de- 

 veloped as in the female, inasmuch as they either correspond in form 

 with those met with in the new-born child, or, in larger glands, are 

 more branched, and furnished with a certain number of terminal vesi- 

 cles, which, on account of their considerable size (they are three times 

 as large as the gland-vesicles in the female), are not to be regarded as 



