ry} *, 5 a ee 
680 THE ORGANS OF SENSE. 
freely anastomosing venous plexus, which, in some parts, eg. over the inferior 
turbinated bones, forms a kind of cavernous tissue (plexus cavernosus concharum). 
Many acinous 
round nuclei 
Basal cells 
Zone of oval +4 q agua tloe a iad | tole a0/L8)4 Bote ogre § g ands, Secr eting a 
nuclei NAN ald yl Way 4 lel 4a) | (|| Nh \p\@, @ Epithelium watery fluid, are 
Zone of PATNA Aes 2°41) a allio Ge Oj aa 8 @ SAA oe eee 
6 IS\cip! 9.999) NON IX, C2 embedded in it, and 
” Duet of one = nae ig We 
of Bowman’s are especially large 
Bente and numerous in 
the posterior half 
of the nasal fossze, 
while in children 
it contains a con- 
siderable amount of 
adenoid tissue. 
In the olfactory 
region the mucous 
membrane 18 
yellowish in colour 
and more delicate, 
and is covered by 
non-ciliated colum- 
| nar epithelium 
Fie. 491.—SEcTION THROUGH THE OLFACTORY Mucous MEMBRANE. : I 9) 
(Figs. 491, 492). 
Glands of Bowman 
Embedded in it are numerous tubular and often branched glands, the glands of 
Bowman (gl. olfactoriz); these are lined by polygonal cells and open by fine ducts 
on its free surface. The epithelium covering the olfactory region consists of: 
(1) supporting cells, . 
(2) olfactory cells, and if |} 
(3) basal cells. Olfactory \\e— Olfactory 
1. Supporting Cells. hairs pa 
— The outer part of 
these cells is columnar 
in shape and contains “supporting _ age 
fine granules of yellow celle | maa 
pigment, whilst the i\* cell” 
deeper portion is at- olfactory i] 
tenuated and frequently ss 
branched. They contain 
elliptical or oval nuclei, Gener 
=|KS rs = ¢ , processes of _ 
which are situated at the rte tory 
deep end of the columnar cells 
part of the cell and form 
what is termed the zone 
of oval nuclei. 
2. Olfactory Cells.— 
They are spindle-shaped 
and lie between the 
- deeper, attenuated parts 
of the supporting cells ; 
their nuclei CMe circular Ate Eirosy ioe , C. Human (vy. Brunn). 
and form the zone of B. Human f © Schultze. 
round nuclei. Each cell | 
gives off a peripheral and a central process, the former of which is rod-like and 
ends on a level with the free extremities of the supporting cells, where it is 
surmounted by a pencil of short filaments, termed the olfactory hairs. A fine 
membrane, the membrana limitans externa, covers in many animals the free 
surface of the epithelium, and is pierced by the olfactory hairs and by the ducts 
of Bowman’s glands. 
The central process is a very delicate varicose filament, which passes inwards 
Central 
process 
Fic. 492.—OLFACTORY AND SUPPORTING CELLS. 
