402 



NORMAL HISTOLOGY. 



CHAPTER XIX. 



THE NASAL MUCOUS MEMBRANE. 



THE mucous membrane lining the nasal fossae consists of two prin- 

 cipal divisions, that of the respiratory and that of the olfactory 

 region ; the latter alone is concerned in the sense of smell. 



The mucous membrane of the respiratory region is dis- 

 tinguished from that of the olfactory area by its thickness, over the 



inferior turbinals it 



FlG -4o8. reaching 4 mm., 



and by the presence 

 of venous net- 

 works of such size 

 that the structure 

 appears as if com- 

 posed of cavernous 

 tissue. The epi- 

 thelium of this 

 region is stratified 

 ciliated columnar 

 in type, within the 

 superficial layer of 



rr^\ 

 The 



Section through mucous membrane of respiratory region of child's WHICH 



nose: a, ciliated epithelium; b, tunica propria ; c, submucous con- goblet-Cells 



nective tissue ; d, mucous glands ; e, duct of glands opening on free . 



surface ; /, blood-vessels. interspersed. 



tunica propria of 



this region is composed of fibrous connective tissue containing clefts 

 occupied by many leucocytes, the latter frequently invading the 

 superimposed epithelium ; occasional nodules of lymphoid tissue 

 are also encountered in various parts of the mucosa. The surface 

 of the tunica propria is smooth, since the usual subepithelial papillae 

 are here wanting. 



The mucous membrane of the respiratory region is further dis- 

 tinguished by numerous small racemose glands, which open on 

 the free surface by funnel-like pits, readily recognized by the unaided 

 eye, and lined for some distance by epithelium corresponding to that 

 of the adjacent surface. These glands are mixed in character, 

 since some acini secrete serous fluids, while others elaborate 

 mucous products. The glandular structures occur with especial 

 frequence over the inferior turbinated bones, although on the lateral 



