XXXVII.] MAMMARY GLAND. 393 



Methods. It is rare to obtain the human uterus sufficiently 

 fresh for microscopical preparations. Harden the uterus of a 

 bitch, cat, or rabbit, in chromic and spirit fluid, alcohol, or Mailer's 

 fluid. Make T.S., and treat them as the Fallopian tube. 



T.S. Uterus. (a.) Observe the serous, muscular, and mucous 

 coats as in the tube, but here the muscular coat is very thick, and 

 is composed of numerous fibres arranged in bundles and running in 

 all directions. The arrangement of these bundles is much simpler 

 in animals than in the human uterus. 



(I.) The mucosa is very thick, and is covered by a single layer 

 of cylindrical nucleated cells, and has numerous glands, which are 

 lined by similar cells. Not un frequently the gland-tubes branch, 

 especially near their lower extremities. It is difficult to retain the 

 cilia on the epithelium lining the cavity of the uterus and its glands. 

 Between the tubules is a relatively large amount of connective 

 tissue containing many nucleated corpuscles and blood-vessels. As 

 the glands pursue a curved course, and do not always run at right 

 angles to the mucous surface, it is difficult to obtain a section, 

 through the entire length of a gland (fig. 364). 



LESSON XXXVII. 



MAMMARY GLAND, UMBILICAL CORD, AND 

 PLACENTA. 



THE mammary gland is a compound racemose gland, but it has 

 about twenty galactoferous ducts which open on the nipple, each 

 duct being dilated into a small reservoir just before it ends on the 

 surface. The ducts, when traced backwards, branch and end in 

 acini or saccular alveoli. The alveoli as in all glands vary in 

 appearance according as the gland is or is not active. The walls of 

 the ducts and acini consist of a basement membrane, said to be 

 composed of branched cells, which in the acini is lined by a single 

 layer of somewhat flattened polyhedral secretory cells. A cluster 

 of acini gives origin to one of the larger ducts, and a considerable 

 amount of connective tissue lies between groups of acini. In fact, 

 the connective tissue greatly preponderates. During lactation the 

 secretory cells are taller and larger, and in their interior probably 

 formed from and by the protoplasm of the cells themselves are 

 formed the fatty granules which are discharged to form the milk 

 35 



