DIRECTIONS FOB LABORATORY WORK 795 



(3) Make l.p. sketch (219) of a primary lobule (histologic and 

 functional unit), including: a, transition from respiratory (terminal) 

 bronchiole to b, alveolar duct ; c, atria ; d, pulmonary sacs ; e, pulmonary 

 alveoli. Study the several portions of the primary pulmonary lobule 

 under the high power and note the structural differences. At what point 

 in the lobule does the smooth muscle end? Where do the lymphatics 

 end? Relative abundance of the elastic fibers? Relation of pulmonary 

 artery and vein to the primary lobule? Define a secondary pulmonary 

 lobule (anatomic unit). 



(4) Make h.p. sketch (220) of wall of pulmonary alveolus (air cell)* 

 cut tangentially. Note the flat respiratory cells and the expansive non- 

 nucleated respiratory plates. 



(5) Sketch (221) several adjacent alveoli from a section of an in- 

 jected specimen of the cat's lung. 



(6) Make h.p. sketch (222) of small extent of the visceral pleura. 



(7) Consider the distribution of the lymphatics, the lymph nodes, 

 lymph nodules and the more diffuse lymphoid tissue in the lung. Func- 

 tion of lymphoid tissue in the lung? Relation to inhaled dust? to 

 infecting bacteria? to tuberculosis^ Consider also the distribution and 

 relative abundance of smooth muscle and of elastic fibers. Significance ? 

 Relation to asthma? to anaphylaxis, e.g., in guinea pig? Explain ab- 

 sence of bronchial veins beyond the bronchioles. 



XIV. THE ALIMENTARY TRACT 



(Digestive Canal) 



(A) THE LIP. 



(1) Study l.p. stained section (vertical) of lip. Distinguish cuta- 

 neous and mucous surfaces. Note : a, bundles of striped muscle fibers of 

 orbicularis oris muscle in transverse section; b, mucous glands; c, hair 

 follicles; d, sweat glands; e, sebaceous glands; f, coronary (labial) ar- 

 tery. Sketch (223). 



(B) THE TEETH. 



(1) Study a stained axial section of a decalcified molar tooth within 

 its alveolar socket. Note: a, crown; b, neck; c, root; d, fangs; e, pulp 

 cavity; f, root canal; g, foramen apicis dentis. Sketch h.p. (224) small 

 area of a, enamel ; b, dentin ; c, cementum ; d, dental pulp reticulum ; e, 

 granular layer of Tomes; f, an odontoblast with its Tomes' fibril within 



