I4I6 



HUMAN ANATOMY. 



The epithelium is stratified ciliated columnar in type, from ,050 -.070 mm. 

 thick, and includes the tall surface cells, bearing the cilia, between the inner ends of 

 which lie the irregularly columnar basal cells. Numerous elements exhibit various 

 stages of conversion into mucous-containing goblet cells. The current produced by 

 the cilia is toward the posterior nares. 



Beneath the epithelium stretches the membrana propria or basement membrane, 

 that varies greatly in thickness ; although in certain localities feebly developed, it is 

 usually well marked and measures from .010-. 020 mm. in thickness (Brunn). 



Fig. 1 1 Si. 



Glands 



Section of respiratory mucous membrane covering nasal septum. X 75. 



Under pathological conditions its thickness may increase fourfold or more. In many 

 places the membrana propria is pierced by minute vertical channels, the basal canals, 

 in which connective-tissue cells and leucocyctes are found, but never blood-capillaries 

 (Schiefferdecker). 



The tunica propria consists of interlacing bundles of fibro-elastic tissue which 

 are most compactly disposed towards the subjacent periosteum. The looser super- 

 ficial stratum is rich in cells and here and there contains aggregations of lymphocytes 

 that may be regarded as masses of adenoid tissue (Zuckerkandl). In certain parts 

 of the nasal fossa the stroma of the mucous membrane contains vascular areas com- 

 posed of numerous intercommunicating blood-spaces that confer the character of a 

 true cavernous tissue. These specialized areas, the corpora cavernosa, as they are 

 called, are especially well developed over the inferior and the lower rnargin and 

 posterior extremity of the middle conchae, and less so over the posterior end of 

 the upper turbinate and the tuberculum septi. When typical, they occupy practically 

 the entire thickness of the mucous membrane from periosteum to epithelium, the 

 interlacunar trabeculae containing the glands and blood-vessels destined for the sub- 

 epithelial stroma. The blood-sinuses, the general disposition of which is vertical 

 to the bone (Zuckerkandl), include a superficial reticular zone of smaller spaces 

 and a deeper one of larger lacunae. The engorgement and emptying of the cavernous 

 tissue is controlled by nervous reflexes and probably has warming of the inspired air 

 as its chief purpose (Kallius). 



The glands of the respiratory region are very numerous, although varying in 

 size, tubo-alveolar in form and, for the most part, mixed mucous in type. The 

 chief ducts open on the free surface by minute orifices barely distinguishable with the 

 unaided eye. Their deeper ends branch irregularly into tubes that bear the ovoid 

 terminal alveoli. The latter are lined with mucous-secreting cells, between which lie 



