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Topography of the nasal glands in rats and some other mammals.

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Topography of the Nasal Glands in Rats
and Some Other Mammals
FINN BOJSEN-MBLLER
Department of A n a t o m y a n d Histology, Royal Dental College,
Copenhagen, Denmark
ABSTRACT
The topography of nasal glands in rats, guinea-pigs, rabbits, cats, and
monkeys was studied in osmium tetroxide and PAS-stained whole mounts and ordinary sections. In rats Bowman's glands in the olfactory region were arranged i n
rows between the branches of the olfactory nerve. Mucous acini were only found o n
the rat septum in connection with Jacobson's organ, and serous acini were found on
the septum posteriorly in the respiratory region, and on the lateral wall of the nasal
cavity around the maxillary sinus ostium. No mixed glands were present. All the
serous glands discharged their secretion through long excretory ducts into the ostium
internum of the vestibule of the nose. In this area rats had 15-20 duct openings on
each side. On the basis of considerations regarding airstream and pressure in the
vestibule, the hypothesis is advanced that the openings act as small nozzles humidifying the inspired air by their atomized secretion. Since no serous or mucous glands
in the rat open on the surface in the nasal cavity proper, it is concluded that the
surface mucous sheet is derived exclusively from the goblet cells and Bowman's
glands. In the other mammals the opening of the serous glands showed a similar
pattern.
The nasal cavity is provided with mucous and serous glands in the lamina propria and with goblet cells in the epithelial
layer.
The secretion of the mucous cells forms
a sheet of mucus which lines the surface
of the nasal cavity. By the ciliary function of the epithelium, this sheet is exchanged several times an hour (Hilding,
'32). There is a constant flow of mucus in
rodents in two directions, from the posterior, larger part of the nasal cavity toward
the pharynx and from the anterior part
toward the nostrils (Lucas and Douglas,
'34).
This mucus exerts a protective effect. It
can entrap foreign particles and bacteria
and remove them from the nasal cavity.
Moreover, it has a waterproofing action,
preventing an excessive transudation from
the tissue into the lumen and an inward
osmotic passage of water which becomes
condensed on the surface during expiration (Negus, '58). The ciliary function depends on the mucous sheet and its viscosity. Lastly, the moist surface subserves the
sense of smell, being the medium in which
the olfactory molecules are dissolved.
Humidification of the inspired air is effected by transudation through the thin
ANAT. REC., 250: 11-24.
epithelium and by the function of the serous glands, while the mucus itself is not
believed to be concerned with this process
(Negus, '58).
According to the type of the epithelium
and glands, the mucous membrane on the
septum as well as on the lateral nasal walls
is divided into a respiratory and an olfactory region. On a fresh specimen the junction between the two is discernible, as the
olfactory region often shows marked yellow pigmentation.
The glands in the respiratory region may
be divided into a medial group on the septum and a lateral group on the lateral wall
of the nasal cavity.
This latter group includes a gland whose
body is beneath the mucosa of the maxillary sinus, as a rule in its anterior wall or
around the ostium of the maxillary sinus.
From this site, a large excretory duct proceeds beneath the mucosa of the middle
meatus, opening at the nostril, frequently
just anterior to the nasoturbinal. This
gland is called the lateral nasal gland or
Steno's gland, as it was described by the
Danish anatomist Steno in 1664. Meyer
('03) described this gland in a number of
domestic animals, int. al., dogs, cats, goats,
pigs, and horses. He found it to be par11
12
FINN BO JSEN-M@LLER
ticularly large in dogs, in which the mucous membrane of the maxillary sinus
may be several millimeters thick. In cats,
on the other hand, the gland and duct are
demonstrable only microscopically, and
in the cow it is absent. It is a serous gland,
and it has intercalated ducts as well as
secretory ducts. The main excretory duct
is lined with simple or pseudostratified
columnar epithelium changing into stratified squamous epithelium a short distance
from the opening.
Broman ('21 ) studied the occurrence
and development of the nasal glands in a
number of rodents, using serial sections of
the nasal cavity from fetuses of various
stages and from newborn young. On this
basis, he made plastic reconstructions of
the nasal mucosa, its glands and ducts.
He found the following groups of glands:
( 1 ) olfactory glands specific of the olfactory region, ( 2 ) anterior lateral nasal
glands whose acini and ducts are situated
in the lateral wall of the nasal cavity and
open into the vestibular part or into the
anterior part of the respiratory region, (3)
maxillary gland opening along the edge
of the maxillary sinus, ( 4 ) anterior medial
nasal glands whose acini and ducts are
situated on the nasal septum and which
open into the vestibular part or the anterior part of the respiratory region, (5)
posterior medial nasal glands, an inconspicuous group of glands situated below
Jacobson's organ, ( 6 ) glands which open
into Jacobson's organ, and (7) infraseptal
glands situated below the anterior part of
the septum and opening on the lateral wall
of the vestibule.
Acini belonging to the anterior lateral
nasal glands are scattered in the respiratory region on the nasoturbinal, on the
maxilloturbinal, and in the middle meatus,
right back to the area surrounding the
maxillary ostium. Hence, the ducts proceed forward, and all open at the junction
to the vestibule, either on the free edge of
the maxillo- or nasoturbinal or in the middle meatus. Broman numbered the glands
chronologically according to the stage at
which they were laid down. Thus, Steno's
gland, which was laid down first in all the
animals, he called gld nasalis lateralis anterior I. In the mouse he found about 20
and in the rabbit about 40 lateral glands.
Acini belonging to the anterior medial
nasal glands are situated in the respiratory region above Jacobson's organ as well
as anterior and inferior to the olfactory region. In many species they may be divided into an upper and a lower group.
The ducts proceed forward and all open at
the junction to the vestibule. These glands
were also numbered chronologically according to the time at which they were
laid down. In the mouse he found four
and in the rabbit about 13 medial glands.
The glands belonging to Jacobson's organ are situated, also according to Broman, in two rows along the borders of the
olfactory epithelium. Their degree of development differs in the various rodents.
It is characteristic of the mouse and rat
that gland no. 2 in the upper row from the
anterior aspect gets particularly large and
branches into the septa1 mucosa.
Bang and Bang ('59) found in histological sections that the lateral nasal gland in
most vertebrates, e.g., chickens and carnivores, is a compound gland with a single
efferent duct opening into the vestibule,
whereas rodents and rabbits have a network of accessory ducts in addition to the
primary duct of Steno, each draining its
particular portion of the gland and discharging into the vestibule.
In guinea-pigs, hares, and dogs the
glands of the respiratory region are said to
be purely serous, while in cats they are
purely mucous (Negus, '58). In man these
glands are compound tubulo-alveolar, of
the mixed type in which mucous acini
predominate. The acini are usually purely
mucous or purely serous, although mixed
acini with serous demilunes may be found
(Heiss, '36). The glands have no intercalary or secretory ducts. The small excretory ducts pass obliquely to the surface,
ending in a funnel-shaped opening. The
larger excretory ducts are scattered in the
respiratory region, but chiefly at its junction to the vestibular part. The epithelium
lining these ducts is simple columnar, but
in the largest ones sometimes pseudostratified. Close to the opening it assumes the
nature of the surface epithelium, acquiring
ciliated cells and goblet cells (Schiefferdecker, 00). According to Brunner ('42),
the human glands open into crypts in the
mucous membrane, but as the excretory
THE GLANDS IN THE MAMMALIAN NASAL CAVITY
13
ducts are long the openings are seldom tated. After removal of the lower jaw, the
seen.
heads were divided sagittally, on each side
Lastly, there are in the respiratory re- of the septum, by a sawblade mounted in
gion numerous goblet cells placed singly in a dental burr drill. Another sagittal secthe epithelium or in groups forming the tion was applied through the maxillary
so-called intra-epithelial glands.
sinus, as close as possible to the nasal
The olfactory region has only one kind mucosa. This gave three specimens, one
of gland, viz. Bowman's. In man, these
are compound tubulo-alveolar glands, of each lateral wall and one of the septum.
As a rule, the mucosa on one side of the
while in the rat they are simple tubular.
septum
was dissected with a blunt instruMorphologically they resemble the serous
glands, but DeVanna and Salonna ('53) ment, the entire specimen being divided
consider them mucous, as they stain by into two equal parts, each consisting of a
the periodic-acid-Schiff (PAS ) technique. lateral wall and the mucous membrane
Bang ('61) described the surface pat- from the corresponding part of the septern of mucous glands in PAS stained tum. In some cases, especially when dealwhole mounts of nasal organs of chickens ing with the small animals, this partition
and herring gulls. She found the glands was not quite successful, so that one half
aligned in rows on the lateral wall as well of these preparations had to be excluded.
as on the septum and the direction of the
One part of each specimen (comprising
flow of the mucous sheet to be consistent a lateral wall and the corresponding septa1
with this pattern. Apart from the study of mucosa) was fixed for an hour in 0.2%
Broman ('21) mentioned above, no similar osmium tetroxide buffered to pH 7.2 by
studies of the glandular topography in the veronal sodium (Palade, '52). The tissue
nasal cavity of mammals and man appear was dehydrated in alcohol and cleared in
to have been reported. Moreover, the study anise oil as described by Aurell ('38).
of Broman does not seem to be mentioned From electron microscopic studies it is
in the recent literature. A knowledge of well-known that osmium tetroxide does not
the situation of the glands and the course merely fix, but also stains tissue. This
and opening of their excretory ducts is technique of preparation distinctly sets
important, if their function is to be under- out all acini and excretory ducts; vessels
stood. The present paper describes the are only faintly visible, whereas nerves
findings in rats and some other mammals stain deeply. Connective tissue stains
on the basis of a combination of sections faintly, whereas cartilage shows marked
and whole mounts stained with PAS and blackening. Therefore, the technique often
osmium tetroxide respectively. This gives fails in handling specimens which are
a good three-dimensional understanding more than a couple of mm in thickness
without any need for serial sectioning of and which contain these elements. They
these large specimens.
turn a diffuse black which masks all details. Another disadvantage is the slow
MATERIAL AND METHODS
penetration of osmium into the tissue. In
The material comprises nasal cavities thick specimens the superficial structures
from 16 rats, two guinea-pigs, two rabbits, stain too deeply before the osmium has
one cat, and one monkey. Four of the had time to penetrate into and stain the
rats were adult, six were four weeks of deep parts. This may be counteracted to
age, five were two weeks and one was one some extent by using a weaker dilution of
week of age. All the other animals were osmium tetroxide and a correspondingly
adult. Histological sections were made : longer staining period. We selected a
of the entire nasal cavity from four rats, 0.2% solution which proved suitable in
of a septum from a guinea-pig, and of a the majority of cases.
lateral nasal wall from a rabbit. The reThe method is applicable even though
mainder of the material was studied in the tissue has already been fixed in forwhole mounts.
malin and stored in alcohol. If so, the
The animals were anesthetized with staining with osmium tetroxide also has
Nembutal intraperitoneally and decapi- to be prolonged.
14
FINN BOJSEN-MGLLER
The remaining part of the septum and
the other lateral wall were fixed for
24 hours in formol: alcohol (1 : 2 ) , PAS
stained, dehydrated, and cleared in anise
oil (Moe, '52).
India ink (diluted with 0.9% sodium
chloride 1 : l ) heated to 37°C was injected
into the aorta of two rats. The septum
was then removed and fixed for 24 hours
in formalin, dehydrated, and cleared in
anise oil.
The whole mounts were studied in a
stereo microscope.
The nasal cavity from four rats was
dissected in toto, fixed in formol: alcohol
( 1 : 9 ) for 24 hours, and decalcified in
formic acid. Two of these specimens were
cut into frontal serial sections and stained
with hematoxylin-eosin. The other two
were cut in three areas, viz. at the junction
of the vestibule and nasal cavity, centrally
and posteriorly in the cavity. These sections, 7-10 CI in thickness, were stained
with hematoxylin-eosin, PAS, PAS after
being pre-treated with diastase for an hour,
and PAS
hematoxylin. Lastly, a few
sections were stained with a pentachromic
stain containing Alcian Blue (Movat, '55).
+
RESULTS
Rat
As is apparent from figure 1 and table 1
the nasal septum may be divided into five
zones according to its surface epithelium
and glandular content.
Serous glands are present only in Zones
I and 11. They do not stain with PAS or
,;---/'
'\.
Fig. 1 Diagram of the right side of the rat
nasal septum. For classification into zones cf.
table 1.
Alcian Blue. On each side of the septum
there are four or five glands, two large
and two or three smaller ones (figs. 2 and
3 ) . Each gland consists of acini situated
mainly in the posterior half of Zone 11,
and a long excretory duct opening into
the vestibule. The openings of the two
largest glands may be seen superiorly and
centrally on the vestibular part of the
septum. From this site, the ducts course
together upward-backward, parallel to the
dorsum nasi. A short distance from the
olfactory region they curve downwards,
forming in the posterior part of Zone 11
a spiral-shaped or S-shaped coil (fig. 2 ) .
The two or three somewhat smaller
glands are situated at the upper and lower
limits of Zone 11, where they send a fairly
straight excretory duct to the vestibule.
They open in varying sites on the anterior
part of the tuberculum septi.
In the anterior third the ducts receive
no tributaries, while in the posterior twothirds they receive branches at right angles
(monopodic branching). These branches
arise in the acini which are situated as
TABLE 1
Types of epithelium and distribution of glands i n the different zones o f the
nasal septa1 mzicosa i n the rat
Region
Epithelium
Serous
glands
Vestibule
zone I
stratified squamous
-
Respiratory
area
zone I1
pseudo-stratified
ciliated columnar
I
Respiratory
area
zone I11
pseudo-stratified
ciliated columnar
Respiratory
area
zone IV
pseudo-stratified
ciliated columnar
-
Olfactory
area
zone V
olfactory
-
Mucous
glands
Goblet
cells
Bowman's
glands
-
-
-
+
+
-
Fig. 2 Part of nasal septum viewed from the right, comprising Zone I1 and the adjacent parts of
Zones I, 111, and V. Two-week old rat. Osmium tetroxide stained whole mount. S: serous glands in
Zone 11. M: mucous glands in Zone 111. B : Bowman’s glands in Zone V. Posteriorly in Zone I1 a
spiral-shaped curling of a serous gland. Note the acini situated as clusters along the excretory ducts.
x 23.
\
’
I
f
rnUCOUS Y / a n d 5
Fig. 3 Diagram showing serous and mucous glands on the nasal septum of the rat. The ducts of
the serous glands course forward and open into the vestibule. The mucous glands empty into Jacobson’s organ which is situated along the lower margin of the septum (the organ is not shown in the
diagram). In the olfactory region note the olfactory nerves, some of which continue to Jacobson’s
organ.
16
FINN BOJSEN-MQLLER
small clusters along the main excretory
ducts. They are particularly densely arranged posteriorly, while more anteriorly
they decrease in size as well as in number.
The glandular ducts on the septum are
situated fairly deeply in the lamina propria
and anteriorly they are frequently sur-
rounded by pseudocavernous tissue (fig. 4).
At the opening they curve obliquely towards the surface and may open at its
level or on a small conical elevation. The
ducts are lined with simple columnar epithelium. The nuclei are centrally located
in the cells, the cytoplasm eosinophilic
Fig. 4 Frontal section through the nasal cavity at the junction to the vestibule. Twoweek-old rat. Hematoxylin-eosin. The cavity is lined with stratified squamous epithelium
except i n its upper part where the epithelium is pseudostratified columnar. Numerous excretory ducts in the middle meatus and on the niaxilloturbinal. On the septum inferiorly
there are two and superiorly three ducts surrounded by cavernous tissue. Note the glandular
openings on the free edge of the nasoturbinal and in the middle meatus (arrows). S: duct
of lateral nasal gland of Steno. L: nasolacrimal duct. Below the septum three excretory
ducts ( x ) surrounded by serous acini. x 45.
THE GLANDS I N THE MAMMALIAN NASAL CAVITY
with basal striation. Before reaching the
opening, the epithelium changes into
pseudostratified and thereupon assumes
the nature of the surface epithelium, viz.
stratified cornified squamous epithelium.
The ducts are 30-40 u in diameter. The
study did not reveal any acini opening
direct on the surface in the respiratory
region.
In the India ink-injected whole mounts
there was pseudocavernous tissue surrounding the anterior part of the glands
and the openings of the ducts. For instance, the tuberculum septi contained a
good deal of pseudocavernous tissue,
In the sections serous acini were found
also in a cavity in the osseous tissue below
the anterior third of the septum (= Broman’s gld. infraseptalis) (x, fig. 4 ) . These
acini empty into two large excretory ducts
which may be followed in the serial sections. The ducts course forward and open
17
anteriorly on the floor of the vestibule or
somewhat higher up on its lateral wall.
Glands in which the cytoplasm showed
diastase-resistant PAS positivity and which
stained with Alcian Blue were interpreted
as mucous glands. They are situated as a
coherent cluster indicating Zone I11 (figs.
3 and 5). These glands fill the entire
lamina propria in this zone. All acini
empty into one or two large excretory
ducts coursing forward - downward and
opening into Jacobson’s organ at the junction between its posterior two-thirds and
anterior third. In addition, the mucinous
acini situated within the capsule of the
organ, i.e. the actual glands of Jacobson,
send numerous small excretory ducts into
the two parallel grooves found at the junction between the olfactory and columnar
epithelium of the organ. Thus, the secretion of all the mucous glands of the respiratory region of the septum is discharged
Fig. 5 Nasal septum. Four-week-old rat. PAS stained whole mount. The apex nasi on the right,
choana at the bottom on the left. In the olfactory region Bowman’s glands are visible as delicate dots
arranged in a linear pattern. In the respiratory region the mucous glands may be seen collected in
one area i n the lamina propria (Zone 111, cf. fig. 1 ) . x 10.
18
FINN BOJSEN-MGLLER
into the organ of Jacobson, which is situated along the base of Zone 111. In this
way these mucous glands are analogous to
Bowman’s glands of the olfactory region.
E n route to the olfactory region and the
lamina cribrosa, the large nerves which
issue from Jacobson’s organ divide the
mucous glandular area into four or five
wide belts.
Goblet cells are present throughout
Zone 11, 111, and IV. As a rule, they occur
singly and seldom make up intraepithelial
groups. They are most densely arranged
in Zone IV around the choanae and inferiorly in Zone 111.
Bowman’s glands are present only in
Zone V which corresponds to the olfactory
region. They are PAS positive, simple
tubular glands traversing the entire lamina
propria. The PAS positive granules are
localized particularly in the subepithelial
portion of the glands, although scattered
granules may be seen in the cells found
in the profound part of their intraepithelial course. As is evident from figure 5
the glands are arranged in rows converging towards the lamina cribrosa. Presumably, this represents a purely mechanical
phenomenon, caused by the olfactory
nerves which partly supply the region
itself and partly proceed to Jacobson’s
organ. As is apparent from the sections,
the nerves fill almost the entire lamina
propria, the glands being situated in the
interstitial spaces (fig. 6).
The lateral wall of the nasal cavity in
the rat may be divided into three zones
according to its surface epithelium and its
glandular content (fig. 7 and table 2).
The serous acini are situated immediately beneath the surface epithelium in
the entire middle meatus and anterior as
well as inferior to the maxillary sinus
ostium (fig. 8 ) . They empty into 10-12
long ducts, coursing forward in the middle
meatus. A short distance before reaching
the vestibule, a number of the ducts curve,
either cranially or caudally, until they
reach the root of the nasoturbinal and the
maxilloturbinal respectively and continue
out to open on their side or on their free
edge (fig. 4 ) . The remaining ducts open
anteriorly in the meatus. Just as on the
septum, the simple epithelium of the ducts
changes, before the opening, into pseudo-
stratified, and then into stratified q u a mous epithelium.
There is, moreover, a large group of
acini around the maxillary sinus ostium,
extending from the above-mentioned acini
and further lateral into the anterior wall
and the floor of the maxillary sinus. The
acini have a narrow lumen surrounded by
epithelial cells which have basal nuclei
and a cytoplasm which stands out dark
and granular when stained with hematoxylin-eosin. Morphologically, they resemble serous acini, but the cytoplasm stains
red with PAS and blue with Alcian Blue,
although the stain is much paler than in
the typical mucous glands. By the present
technique, therefore, it is impossible to
group these acini either as mucous or
serous. Presumably, they are serous. Between the acini there are many secretory
ducts which empty into a large excretory
duct running forward-upward in the middle meatus. A short distance from the
root of the nasoturbinal it curves forward
and courses parallel to the line of attachment of the turbinal to the vestibule
(fig. 8 ) . In the whole mounts it stands
out darker and thicker than the other
ducts and is consequently easy to trace.
This is the gland which has been described
as the lateral nasal gland or Steno’s gland.
In the sections it shows a pseudostratified
epithelium with two rows of cuboidal cells
unlike the other excretory ducts which
have predominantly a simple epithelium.
Its diameter is about 60 11, that of the
other ducts 30-40 ~1 (fig. 4).
Goblet cells are present only in the
respiratory region in which they are particularly densely arranged on the medial
aspect of the maxilloturbinal. As on the
septum, there are only a very few intraepithelial groups of goblet cells.
Bowman’s glands are found in the olfactory region where they are aligned, as on
the septum, between the nerves which
converge towards the lamina cribrosa.
In the whole mounts the nasolacrimal
duct is visible inferiorly on the lateral wall
where it runs forward, medial to the upper
incisor. It also opens in the vestibule, but
even farther anteriorly than the other
glands, the opening being on a level with
the ala of the nose.
THE GLANDS IN THE M A M M A L I A N N A S A L CAVITY
Fig. 6 Frontal section through the nasal septum showing the olfactory region. Two-weekold rat. PAS stained. Bowman’s glands are situated between the olfactory nerves. The subepithelial part and some of the intra epithelial part of the glands are stained. Close to the
osseous septum there are branches of the ethmoidal artery. x 120.
I
Fig. 7 Diagram showing the lateral wall of the nasal cavity in the rat. For classification
into zones, cf. table 2.
19
20
FINN BO JSEN-MC~LLER
TABLE 2
T y p e s of e p i t h e l i u m a n d distribution of glands in t h e different zones of t h e
lateral wall of the nasal cavity in t h e r a t
Region
Serous
glands
Epithelium
Mucous
glands
Goblet
cells
Bowman’s
glands
Vestibule
zone I
stratified squamous
-
-
-
-
Respiratory
area
zone I1
pseudo-stratified
columnar
+
-
+
-
Olfactory
area
zone I11
olfactory
-t
g l . na salis l a t Stenonis
OQSO
turb6
fhmo f urbinals
ostium sinus ma.uUaris
audio turbina
Fig. 8 Diagram showing the glands on the lateral wall of the nasal cavity in the rat.
The posterior parts of the nasoturbinal and the maxilloturbinal have been removed so that
the course of the glandular ducts i n the middle meatus may be traced. Only a few of the
ducts are demonstrated. Around the maxillary sinus ostium there is a large glandular body
whose main part makes up the lateral nasal gland of Steno. Subepithelially in the same
area the other serous glands take their origin. Unlike the former, the latter glands receive
tributaries from the acini during their course through the middle meatus. Note the openings
of the ducts anteriorly i n the vestibule and on the free edges of the turbinals.
Apart from the rat, another two rodents,
as well as a cat and a monkey, were studied. The same whole mount technique
was used, with fixation and staining in
osmium tetroxide and subsequent clearing
in anise oil. In these larger animals, however, the lateral wall of the nasal cavity
was so thick that during osmium staining
the preparations became so black that they
could hardly be cleared. Consequently,
the main stress was laid on the study of
the septum.
Guinea-pig
On the nasal septum of the guinea-pig
there is a large group of serous acini in
the posterior two-thirds of the respiratory
region. These acini are particularly dense
posteriorly below the olfactory region. In
this area the mucosa is 1.0 mm thick,
while in the other parts of the septum it
is about 0.2mm. From these acini at
least ten long excretory ducts run all the
way to the vestibule. These excretory ducts
course in three strands, one along the
dorsum nasi, one along the floor, and one
in the middle of the septum. In the vestibule the openings may be seen on and
immediately anterior to the tuberculum
septi. In the most anterior portion of the
respiratory region there are, moreover,
some small glands whose ducts course
right forward, opening in the vestibule
together with the larger ducts. In the
THE GLANDS I N THE MAMMALIAN NASAL CAVITY
sections, the acini present themselves with
a small lumen, round basal nuclei, and
a delicately granular, eosinophilic cytoplasm. The excretory ducts are lined with
simple columnar epithelium, the nuclei are
centrally located and the cytoplasm eosinophilic with basal striation. On the lateral
wall there are acini around the maxillary
sinus ostium, extending forward in the
middle meatus. From this site, about ten
excretory ducts proceed to the vestibule.
Rabbit
On the rabbit septum there are about
20 glands on each side. Their acini occupy
a horseshoe-shaped area on the septum,
being localized in the posterior half of the
respiratory region and in two strands along
21
the upper and lower boundary of the septum all the way to the vestibule. The
excretory ducts may be traced throughout
the glandular area, the majority running
superiorly or inferiorly on the septum to
the openings in the vestibule (fig. 9). Posteriorly, they undergo dichotomous division a few times, but otherwise they receive only tributaries at right angles. On
the lateral wall acini are present around
the maxillary sinus ostium and hence all
the way forward, in the middle as well as
inferior meatus, there being about 20 excretory ducts in the middle and about ten
in the inferior meatus. Most of the ducts
in the middle meatus proceed anteriorly
to the nasoturbinal and open on its inferior, free edge. In contrast to the rat,
Fig. 9 Vestibule in an adult rabbit; septum viewed from the right. Osmium tetroxide
stained whole mount. Four ducts and their openings are visible. One duct courses downward-forward, opening a bit more apically than the others. x 45.
22
FINN BOJSEN-M#LLER
the rabbit has no openings on the maxilloturbinal. The ducts are lined with simple
epithelium and are 40-50 LI in diameter.
Around the maxillary sinus ostium there
is, as in the rat, a large cluster of glands
occupying the entire wall between the
nasal cavity and the maxillary sinus (the
lateral nasal gland). The acini resemble
serous glands in hematoxylin - eosin
stained preparations. They stain with
PAS, but not as deeply as e.g. the mucous
glands which are scattered subepithelially
throughout the maxillary sinus. In the
glandular cluster the sections show numerous secretory ducts. They empty into a
large excretory duct which proceeds upward-forward in the middle meatus until
it reaches the nasoturbinal. At this site it
turns straight forward and runs parallel
to the soot of the turbinal until it opens
into the vestibule. It has a pseudostratified
epithelium with two rows of cuboidal cells
and is surrounded by a lamina propria. In
cross section i t is oval and measures 300
X 80 p. The opening is so large that the
canal can easily be injected with a dye
which may be traced to the acini.
Cat
In the cat there are 8-10 PAS positive
glands anteriorly on the septum. Their
ducts proceed parallel, downward-forward,
to the vestibule. In the whole mounts the
openings may be seen aligned on the tu-
berculum septi. The pattern is similar to
that seen in the monkey (fig. lo), although
the glands are shorter. In addition, there
are small groups of PAS positive acini
scattered in the entire respiratory region.
From each of these groups a small excretory duct proceeds straight up to the surface where it penetrates the epithelium.
Cynomolgus Monkey
(inacacus irus)
The monkey is a microsmatic animal
and has only a small olfactory region. On
the septum there are a number of glands
whose ducts cousse parallel with the dorsum nasi down into the vestibule (fig. 10).
The longest of these ducts takes its origin
in the olfactory region. The glands are
shorter in the lower part of the septum.
In the posterior parts there are several
divisions of the ducts, and there are a few
anastomoses. At the openings into the
vestibule there are 15-20 ducts. As in the
cat, acini are scattered in the entire respiratory region.
Current studies on the human septum
have shown that infero-anteriorly in the
region of the internal ostium there is ail
area of about one square cm which has
densely placed glandular openings, 300400 LI in diameter. Whole mounts stained
with osmium tetroxide exhibit ducts proceeding upward-backward from this site.
Hematoxylin-eosin stained sections of the
pn. oifoctorii
n.nusopafatinus
Fig. 10 Diagram of the nasal septum of a monkey (macacus irus) viewed from the
right. The olfactory region is small. The course of the glands and their openings into the
vestibule are visible. Only some of the ducts are demonstrated.
THE GLANDS I N THE MAMMALIAN NASAL CAVITY
anterior part of the respiratory region show
mixed acini in the lamina propria. Excretory ducts of two sizes are discernible:
70-80/~ ducts of a rather superficial level
which often open on the surface and 200400/cl ducts of a deeper situation which
open in the vestibular region. In this respect, the glandular topography in man
appears to resemble that found in the
monkey, although the ducts might be
shorter.
DISCUSSION
It is a basic pattern in all the animals
studied that a large group of serous glands
open around the internal ostium of the
nasal cavity. This was particularly striking in rodents in which all the serous
glands of the nose opened into this zone.
In the rat there were 15-20 glands and
in the rabbit not less than 50 on each side,
apart from the large lateral nasal gland.
The last-mentioned gland was described as
early as 1664 by Steno. Meyer (’03),who
called it Steno’s gland, described the site
of the body of this gland and the course
of its excretory ducts in 15 large animals
in which he could dissect the gland macroscopically, e.g. dog, lion, hyena, camel,
sheep, and horse. In all animals he found
the site of opening in or close to the vestibule except in the horse in which it was
deeper in the nose. On histological study
Meyer found that the glandular cells in
Steno’s gland did not show mucus reaction
and that they had to be interpreted as
serous. He assumed that the function of
the gland was to moisten the inspired air.
Broman (’21) demonstrated that in rodents a number of serous glands, apart
from Steno’s gland, open into the vestibule,
in mice and rats 20-25 and in rabbits
about 55 on each side. This is in keeping
with the present results. Broman assumed
that the function of these glands was to
moisten the inspired air and, that the
serous fluid flowing down past the opening of Jacobson’s organ could carry with
it smelling substances which could temporarily be sucked into this organ.
In a previous paper (Broman, ’18) on
the architecture and function of Jacobson’s organ in some mammals, he also
mentioned these nasal glands. He pointed
out that in animals in which Jacobson’s
23
organ opens into the nasal cavity, e.g.
rodents, the nasal glands are highly developed, while they are less developed or
absent if Jacobson’s organ is absent, as
e.g. in man, or if Jacobson’s organ communicates with the oral cavity, as e.g. in
the cow in which even the most constant
of the large nasal glands, the lateral nasal
gland of Steno, atrophies already in the
embryo.
These studies by Broman of the nasal
glands appear to have been unheeded by
recent literature, and we were not aware
of them until after we had found the
named glandular course.
In the area at the internal ostium there
is the junction of the cutaneous lining of
the vestibule to the mucosa of the nasal
cavity. The internal ostium is at the same
time the narrowest place that the inspired
air passes on its way through the nose.
According to the equation of Bernoullis,
known from hydrodynamics, the pressure
will fall where a flowing fluid or gas is
accelerated in the direction of the stream,
and it will increase where the flow slows
down (= accelerated in the opposite direction). During inspiration the pressure in
the nasal cavity is low and must be particularly low on a level with the openings
of the glands in the internal ostium, as
this is where the acceleration of the airstream is at a maximum. It is tempting
to imagine that the process of humidification is increased also by the way in which
the glandular openings are placed at the
internal ostium. The opening is on a small
conical elevation, on the tuberculum septi
or on the free edge of the conchae. This
orients the ducts against the airstream in
a way which, combined with the low pressure, might permit or favor the process of
humidification by atomizing the discharge,
and in addition this atomized fluid might
entrap olfactory molecules and carry them
to the olfactory region. During expiration
the pressure over the openings is high and
the airstream quieter and slower than during inspiration. Thus, during expiration
the conditions are less favorable for a possible nozzle effect with unnecessary loss
of fluid. The ducts and their openings are
surrounded by pseudocavernous tissue
which swells during the resting phase of
the nasal cycle and thereby slows down the
24
FINN BOJSEN-MCbLLER
passage of air through one-half of the
nose (Stoksted, '56). It might be imagined
that during this process the ducts too are
greatly narrowed, so that the glands do
not discharge any secretion.
This centers new interest on the opening
of the nasolacrimal duct in the vestibule,
since owing to its distant position it must
be assumed to act, in the animals studied,
in the same way as the nasal glands
proper. If so, the lacrimal fluid takes part
in the air conditioning. During inspiration
there must be a pressure gradient over the
canal. This involves the possibility that
it is not solely by capillary action that the
fluid in the lacus lacrimalis is sucked into
the nasolacrimal duct, but that this difference in pressure may be contributory. During expiration there is a pressure gradient
in the opposite direction. If the diameters of the canals may be taken to indicate their share in the nozzle function, the
lacrimal fluid must represent an important
supplement to the humidification of the
air, as the nasolacrimal duct in the rat
measures 350 X 150 CI and in the rabbit
1.6 X 0.5 mm.
While all the serous glands in the rat
open into the nasal vestibule, the secretion
of the mucous glands flows into Jacobson's
organ which in turn opens on the floor of
the nasal cavity. Therefore, in this animal
at least, the blanket of mucus which lines
the nasal mucosa can be derived only from
the goblet cells and from Bowman's
glands.
It has been claimed that transudation of
fluid through the nasal mucosa makes up
the main source of humidification of the
inspired air (Negus, '58). Ingelstedt and
Ivstam ('48) and Messerklinger ('51),
however, could not demonstrate transudation from capillaries and tissue fluid to
the nasal secretion under normal conditions and conclude that nasal secretion is
normally a pure glandular product. This
assumption is supported by the present
findings.
ACKNOWLEDGMENT
The author is grateful to Professor H.
Moe, M.D., Department of Anatomy and
Histology, The Royal Dental College, Copenhagen, for helpful discussions and criticism during the preparation of this manuscript.
LITERATURE CITED
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dicke Schnitte zu mikroskopischen Zwecken.
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Bang, B. G. 1961 The surface pattern of the
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