122 PRACTICAL HISTOLOGY. 



EXAMINATION (L). Observe (a) the serous coat, (If) the muscular coat, very thick, and 

 composed of bundles of non-striped muscle, arranged in many layers. The mucous coat con- 

 sists of fibrous tissue, and is lined by columnar ciliated epithelium (the cilia are difficult to 

 preserve), and in it are seen sections of the uterine glands, which are cut in every direction, but 

 they are simple tubular glands, often branched at their lower extremities, and they are lined 

 throughout by ciliated epithelium (PL XXIX., Fig. 3). 



(H). Observe specially the uterine glands, with their membrana propria lined by ciliated 

 columnar cells. (Indicate a gland in PL XXIX., Fig. 4.) 



Similar preparations ought to be made of the cervix uteri, e.g., of a cow. 



THE MAMMARY GLAND. 



PREPARATION. The best specimens are obtained from a gland taken from an animal 

 near the full period of gestation. Harden small pieces for a week in the chromic acid and 

 spirit mixture ; make sections, stain them with logwood, and mount them in dammar. 



EXAMINATION (L). Observe the framework, which consists of septa, chiefly of lamellar 

 connective tissue, which subdivide the gland into a series of small polygonal lobules. In these 

 septa sections of the large lactiferous or milk ducts, and large blood-vessels are found. 



Study a lobule (L and H). Observe its shape, and note that it consists of a large number 

 of gland alveoli, supported by a very small amount of connective tissue. 



Study an alveolus (H). Observe its membrana propria, lined by a single layer of short 

 columnar epithelial cells. Sections of the large lobular ducts will be readily met with. Fat- 

 globules, i.e. milk-granules, may be seen within the protoplasm of these cells. Osmic acid 

 readily reveals the presence of fatty particles in the cells by blackening them. (Indicate the 

 alveoli, with the cells lining t/iem, in PI. XXX., Fig. i.) 



THE MILK. 



Place a drop of fresh milk on a slide, apply a cover-glass and examine (H). It consists of 

 a large number of oil-granules, of various sizes, floating in a fluid. Each globule consists of 

 an albuminous envelope (Ascherson's membrane), enclosing a globule of oil. Add acetic acid, 

 which partially dissolves the envelope, and then the oil-globules run into little heaps or clusters. 

 Osmic acid blackens them. Do not preserve them. (Delineate in the upper half o/P\. XXX., 

 Fig; 2, ordinary milk, and in the lower half the effect of acetic acid on it.*) 



In the milk shortly after delivery many large nucleated cells, filled with milk-globules 

 the colostrum corpuscles are to be found. Examine these (H). 



THE PLACENTA. 



PLACENTA OF A CAT OR GUINEA-PIG. 



PREPARATION. The animal ought to be killed about the middle of the period of 

 gestation. Open the abdomen and expose the uterus. The uterus is cautiously opened, 



