210 NORMAL HISTOLOGY. 



which the hardening is completed. Sections at right 

 angles to the surface are stained double and mounted in 

 glycerin. 



Isolated Surface-Cells. From a bit of vagina hardened 

 as above, or simply in alcohol, the cells from the surface 

 of the mucous membrane are scraped with a scalpel, 

 stained on a slide with haematoxylin, and mounted in 

 glycerin. Familiarity with the appearances of these 

 surface cells is of practical importance, since they are 

 often found in urine. 



MAMMARY GLAND. 



The mammary gland is a racemose, and when 

 fully developed a tabulated, gland, whose spheroidal 

 and elongated alveoli are formed by a membrana 

 propria composed of flattened cells, and lined with 

 cuboidal epithelium. The excretory ducts, which 

 in each gland are fifteen to twenty in number, and 

 open at the surface of the nipple, are lined with 

 cylindrical epithelium. Fibrillar connective tissue 

 with elastic fibres lies between the alveoli and lobules, 

 and is abundantly furnished with blood-vessels. 



The gland presents, both macroscopically and 

 microscopically, quite marked differences in appear- 

 ance at different times, depending upon age, sex, 

 and, in the adult female, upon whether or not the 

 individual is pregnant, and upon the period of 

 pregnancy and the occurrence of lactation. 



In children, as in the adult male, the gland 

 presents, in general, a system of ramifying ducts, 



