DIRECTIONS FOB LABORATORY WORK 797 



types of lingual papillae: filiform (conical) (234); fungiform (235); 

 circumvallate (vallate) (236); and foliate (237). Note the taste-buds 

 in the latter two types of papillae. 



(3) Study an injected specimen of cat's tongue and note the blood 

 supply of the muscle, and of the several papillae. 



(4) Study a transverse section of the foliate papillae of the rabbit's 

 tongue. Note the numerous taste buds. 



(D) THE PALATE (Palatinum). 



(1) Study a stained longitudinal section of the palate (including 

 the uvula, the soft palate, and a portion of the hard palate), noting the 

 character of the epithelium on the nasal and oral surfaces. Sketch 

 (238). 



(E) THE PHARYNX. 



(1) Study l.p. a stained section of the oropharynx. Note: a, type 

 of epithelium of the mucosa; b, character of the tunica propria; c, 

 lymphoid tissue; d, boundary of fibre-elastic tissue, the representative 

 of both the tela submucosa and the muscularis mucosa of other portions 

 of the digestive tube (the elastic fibers are mostly longitudinally dis- 

 posed) ; and e, the outermost layer of obliquely disposed striped muscle 

 fibers, among the connective tissue of which are embedded many tubo- 

 acinar mucous glands. Sketch (239). 



(F) THE ESOPHAGUS (Gullet). 



(1) Study l.p. a stained transverse section through the lower third 

 of the esophagus. Note the four tunics from within outward : a, tunica 

 mucosa; b, tela submucosa; c, tunica muscularis; and d, tunica adven- 

 titia (fibrosa). In the tunica mucosa, note the type of the epithelium, 

 the character of the corium (lamina propria mucosae), and the lamina 

 muscularis mucosae. (Near the cardiac orifice the muscularis mucosae 

 consists of an incomplete inner layer of circularly disposed smooth mus- 

 cle cells, and a more extensive outer stratum of longitudinally arranged 

 cells; elsewhere in the esophagus generally the latter stratum only 

 occurs; below the esophagus both layers occur.) In the tela submucosa 

 note the character of the tissue and the mucous glands. Do the glandu- 

 lar alveoli contain demilunes? (Mucus-secreting glands are absent in 

 the esophagus of the cat, very abundant in that of the dog, and very 

 variable in man. They are generally more abundant towards the oral 

 end.) In the tunica muscularis, note the two strata of 'smooth muscle 

 cells, the outer longitudinal and the inner circular (at the cardiac orifice 



