NOSE. 



397 



few small glands. A pocket which extends into the lower part of the 

 median septum and is named the vomero-nasal organ [Jacobson's organ], 

 is in man the rudimentary remnant of an important sense organ supplied 



FIG. 447. ISOLATED CELLS OF THE OL- 

 FACTORY MUCOSA OF A RABBIT. X 560. 



st, Supporting cells ; s, extruded mucus re- 

 sembling cilia; r, olfactory cells, from 

 r', the lower process has been torn off ; 

 f, ciliated cell; b, cells of olfactory 

 glands. 



dr[ b 



' -*=- 



b 



Tunica propria. 



FIG. 448. VERTICAL SECTION OF THE OLFACTOR 

 MUCOSA OF A RABBIT. X 50. 



zo, Zone of oval; zr, zone of round nuclei; dr, olfac- 

 tory glands; a, excretory duct; k, body; g, fun- 

 dus; n, sections of the olfactory nerves; v, vein; 

 ar, artery; b, connective tissue. 



\ Epithelium. 



by the olfactory nerves. From the fifth month of fetal life it is lined with 

 a tall columnar epithelium which is not olfactory. 



In the regio olfactoria the mucosa consists of a tunica propria and 

 an olfactory epithelium. The latter consists of sustentacular cells and 

 olfactory cells. The super- 

 ficial halves of the susten- 

 tacular cells are cylindrical, 

 and contain yellowish pig- 

 ment together with small 

 mucoid granules often ar- 

 ranged in vertical rows 

 (Fig. 447). The more slen- 

 der lower halves have den- 

 tate or notched borders, 

 and branched basal ends 

 which unite with those of 

 neighboring cells thus form- 

 ing a protoplasmic network. 



Their nuclei, generally oval, are in one plane and in vertical sections 

 they form a narrow "zone of oval nuclei" (Figs. 448 and 450). The 

 olfactory cells generally have round nuclei containing nucleoli. They 

 occur at different levels and so form a broad "zone of round nuclei." 

 From the protoplasm which is gathered immediately about the nucleus, 



Fibers of the 

 olfactory nerve. 



Centripetal process 

 of an olfactory cell. 



FIG. 449. GOLGI PREPARATION OF THE OLFACTORY REGION- 

 OP A YOUNG RAT. 



