the inferior end of which becomes somewhat wider, and



372 MANUAL OF HISTOLOGY.

brandies into a number of delicate filaments, by means of
which the cell is attached to the fundamental layer of connec-
tive tissue. These widened extremities of the cells often con-
tain a brownish, partly nuclear, partly diffused pigment.
Viewed upon the plane surface, the number of olfactory cells
is apparently larger than that of the cylindrical cells. Each
one of the latter, however, is generally surrounded by six of
the olfactory cells, which completely fill the intermediary
spaces between the cylindrical bodies. Both varieties of cells
are so accurately adjusted to each other that, especially in the
wider portion of the epithelial cells, fine longitudinal furrows
may be seen, into which the peripheral continuations of the
olfactory cells have been received.

The surface of the epithelium is covered by a delicate mem-
brane, discovered by Yon Brunn, and called by him the mem-
brana limitans olfactoria. He has compared it to the membrana
limitans externa of the retina, and describes its free surface as
being plane and even, while its lower surface covers completely
the rounded terminations of the epithelial cells. The periph-
eral prolongations of the olfactory cells pass through this
membrane, and terminate with bare extremities at the level of
its free plane.

The olfactory nerves. The branches from the olfactory
ganglia which emerge through the apertures of the lamina cri-
brosa are composed entirely of non-medullated filaments, which
resemble embryonic nerve-fibres. They next anastomose in the
deeper layers of the mucous membrane, and form a dense
plexiform mesh work, which sends fine branches toward the
surface. In these branches the axis-cylinders are broken up
into numerous, very fine, varicose fibrils, which ascend to the
limit of the epithelial layer, where they are lost. Most au-
thors agree with Schultze that there is a distinct connection
between the nerve-fibrils and the olfactory cells. Exner be-
lieves that the nerve-fibrils connect with the epithelial cells
also. He argues, moreover, that intermediary forms, between
the two varieties of epithelium, are found, which would prove
that they are not different structures, but one and the same.
Neither of these views has yet been established.

Bowman^ s glands, peculiar to the olfactory mucous mem-
brane, are found in it in large numbers. They occupy almost
the whole thickness of the mucous membrane, their bodies be-



THE NASAL FOSSAE, PHARYNX, AND TONSILS. 373

ing located in the deeper layers of the connective tissue. In
man their shape varies somewhat from that of simple tubules,
as several glandular tubes ordinarily unite in a common excre-
tory duct, so that, in some cases, the gland almost appeai-s
racemose. The glandular cells are partly round, partly irreg-
ular in shape, and have many pale nuclei, together with a
brownish-colored pigment.



THE PHARYNX.

The mucous membrane of the pharynx is, in general, simi-
lar to that of the mouth. It consists essentially of a stratified
pavement-epithelium, a rather loosely woven submucosa, which
contains aggregations of mucous glandules, and a tunica pro-
pria composed of fibrillary connective tissue and furnished
with papillae. The papillae are smaller than those found lower
down in the oasophagus. The mucous glandules are most
abundant in the superior part of the pharynx. The mucous
membrane of the vault of the pharynx, and in the vicinity of
the isthmus of the fauces, where it becomes continuous with the
mucous membrane of the nasal cavity, to some extent assumes
the characteristics of the latter. In this region the connective
tissue is more or less thickly interspersed with lymphoid cells.
It is provided, moreover, with ciliated cylindrical epithelium.
In adults this epithelium extends some distance backward until
it passes into the stratified pavement variety. In children,
however, ciliated epithelium lines the whole naso-pharynx.
In the upper and lateral parts of the pharynx are found cer-
tain aggregations of adenoid tissue, most abundantly in the
vault of the pharynx, extending from one Eustachian tube to
the other. This tissue is generally quite diffuse, but is identi-
cal in its structure with the lingual follicular glands arid with
the tonsils, and from this resemblance it has derived the name
"pharyngeal tonsil."

THE TONSILS.

The tonsil consists essentially of a reduplication, more or
less extensive, of the oral mucous membrane, containing in its
folds an abundance of the so-called adenoid tissue.



374 MANUAL OF HISTOLOGY.

Its gross structure varies in different animals. In some the
organ is entirely absent. Its simplest form is found in the rab-
bit, where it resembles a large lingual f ollicular gland. In man
its usual shape is ovoid. Its average vertical diameter is 20
mm., and its transverse diameter 13 mm. Its surface is per-
forated by a varying number of slit-like and circular depres-
sions, the common orifices of the system of cavities which it
contains. If the tonsil of the rabbit be considered a single
follicular gland, we have in man a multiplication of this to the
number of from eight to eighteen, the interval between each
gland forming a " lacuna tonsillaris," crypt, or one of the sys-
tem of cavities mentioned above. There are also in the interior
of the tonsil single larger cavities, each of which includes sev-
eral follicular folds and procures their common discharge at
the periphery. The crypts generally are filled, more or less,
with a yellowish substance composed of fat-molecules, detached
pavement-epithelium, lymph-corpuscles, small molecular gran-
ules, and cholesterin- crystals, which probably proceed from
retained and decomposed epithelial matter, and perhaps now
and then from the bursting of follicles whose cells have in-
creased by proliferation and have undergone retrograde meta-
morphosis and fatty degeneration. In its minute anatomy the
tonsil is for the most part like other so-called adenoid glands.
In common with the rest of the oral cavity, it is invested with
a thick covering of pavement-epithelium, which rests upon a
delicate endothelioid basement-membrane. Following this is a
tolerably compact mucosa, formed of interlacing bands of
fibrous connective tissue and containing many connective-tis-
sue corpuscles. In the normal adult tonsil this structure is so
delicate that sometimes it is hardly recognizable. From it
bands of connective tissue extend centrally into the larger ton-
sillary folds, and the whole forms essentially both an enclosure
and a framework for the adenoid tissue or proper substance of
the gland, as well as a nidus for its vessels. The minute struc-
ture of the adenoid tissue of the tonsil does not differ from
that of other follicular glands (those of the intestine, etc.), de-
scribed elsewhere. Occasionally, in the tonsil the adenoid tis-
sue extends so near the periphery as to penetrate the mucosa
and encroach upon the epithelial layers. This is especially
the case in the walls of the crypts, where the epithelium com-
monly exists in a modified form, or is altogether wanting. The



BIBLIOGRAPHY. 375

tonsil is supplied abundantly with racemose mucous glands,
which are most numerous in the neighborhood of the hilus.
Here, also, may be found small bundles of muscular fibres
apparently independent.



BIBLIOGRAPHY.

KOLLIKER. Ueber das Geruchsorgan von Amphioxus. Miiller's Archiv fur Anat.

und Physiol. 1843.

KOHLRAUSCH. J. Miiller's Archiv, pp. 8, 149. 1853.
ECKER. In Berichte iiber die Verhandlungen zur Beforderung der Naturwiss.

No. 12. Fribourg, 1855.
SCHULZE, MAX. Ueber die Endigungsweise der Geruchsnerven und die Epithelial-

gebilde der Nasenschleimhaut. Monataberichte der konigl. Acad. der Wis-

sensch. Berlin, 1856.
ECKER. Ueber die Geruchsscbleimhaut des Menschen. Zeitschrift f . wiss. Zoologie.

VIII., p. 305. 1856.
ECKER, A. Bericht iiber die Fortschritte, Anafcomie und Physiologic f. d. Jahr

1856, p. 117. Von Henle und Meissner.

TODD and BOWMAN. The Physiological Anatomy of Man. II. London, 1856.
SEEBERG. Disquisitionea Microscopicae de textura membranae pituitaria3 nasi. Diss.

Inaug. Dorpati, 1856.
KOLLIKER. Ausbreitung der Nerven in der Geruchsschleimhaut von Plagiostomen.

Sitzber. der physik.-med. Gesellschaft, T. VIII. , pp. 31. Wurtzburg, 1857.
ERICHSEN. De textura nervi olfactorii ejusque ramorum. Th. inaug. Dorpat,

1857.

HOYER. De tunicse mucosaa narium structura. Berolini, 1857.
ECKHARDT. Ueber Endigungsweise der Geruchsnerven. Beitrag zur Anatomie

und Physiologie. 4. Abhand., p. 97. 1858.
GASTALDI. Nuovi Ricerche sopra la terminazione del nervo olfactorio, in memorie

de 1'Acad. reale della Scienza de Torino. XVII., p. 372. 1858.
FUNKE, O. Lehrbuch der Physiologie. 2. Auflage. 1858.
KOLLIKER. Handbuch der Gewebelehre. 3. Auflage, p. 680. 1859.
HOYER. Ueber die mikroskopischen Verhaltnisse der Nasenschleimhaut. In Miiller'a

Archiv f. Anat. und Physiolog., 1861, p. 287 ; 1860, p. 6.

CLARKE, LOCKHART. Ueber den Bau des Bulbus olfactorius und der Geruchs-
schleimhaut. Zeitsch. f. wissens. Zoologie. XI. 1862.
WALTER, G. Ueber den feineren Bau des Bulbus olfactorius. Virchow's Arch., T.

XXII., p. 261. 1862.

HENLE. Handbuch der systematischen Anatomie des Menschen. Bd. II. Braun-
schweig, 1866.
ZERNOFF. Ueber das Geruchsorgan der Cephalopodon. Bull, de la Soc. imp. des

sc. nat. de Moscow. 2e serie. XLII. 1869.
EXNER. Weitere Studien iiber die Structur der Riechschleimhaut bei Wirbelthie-

ren. Sitzungsberichte der k. Akad. der Wissenschaften. Wien. Band LXV.

3. Abth. 1872. Et Bd. LIII. 1867-1869.



376 MANUAL OF HISTOLOGY.

HEIDENHAIN, A. Ueber die acinosen Driisen der Schleimhaute, ins besondere der

Nasenschleimhaut. Diss. Inaug. Breslau, 1870.
SCHULZE, MAX. Untersuchungen iiber den Bau der Nasenschleimhaut. InAbhand-

lung. d. naturforsch. Gesellschaft. VII. HaUe, 1872.
BABUCHLN. Das Geruchsorgan. In Strieker's Handbuch. 1872.
MARTIN. Studies from the Physiol. Lab. in the University of Cambridge. I. 1873.
CISOFF. Zur Kenntniss der Regio Olfactoria. Centralblatt. 1874.
BIGELOW, H. J. On the Anat. of the Turbinated Corpora Cavernosa. Boston, Med.

and Surg. Journal. April, 25, 1875.
SHOFJELD, B. N. A. Taste-Goblets in the Epiglottis of the Dog and Cat. Journal

of Anat. and Physiol. X., p. 475. 1876.

H5NIGSCHMIED. Ztschr. f. wiss. Zool. XXIX., S. 255. 1877.
DAVIS, C. Die becherf ormigen Organe des Kehlkopf es. Arch, f . mikroskop. Anat. ,

XTV., S. 158. 1877.
PODWISOTZKY. Anatomische Untersuchungen iiber die Zungendriisen des Menschen

und der Saugethiere. Inaugural Dissertation. Dorpat, 1878.
LOWE. Beitrage zur Anatomic der Nase und Mundhohle. S. 20. Berlin, 1878.
ZUCKERKANDL. Ueber die norm, med.-path. Anat. der Nasen- und angrenzenden

Hohlen. All Wien. med. Ztg., No. 51. 1879.
STEINBRUGGE, H. The Histology of the Inferior Turbinated Bones and of the Tele-

angiectatic Fibromata Arising from These. Archives of Otology, New York,

Oct., 1879.



CHAPTER XXIII.

THE MOUTH AND TONGUE.

BY D. BRYSON DELAY AN, M.D.

Curator of the New York Hospital, New York City ; Member of the American Laryn-

gological Association.

WITH the exception of a few remarkable modifications, the
structure of the mucous membrane of the buccal cavity is the
same throughout.

The tunica propria consists of fibrillated connective tissue,
made up of tolerably minute bundles of intertwining filaments.
Between these appear many delicate, elastic fibres. Toward
the epithelium this structure becomes less distinct, and an ex-
ceedingly delicate, filamentous network is developed. The con-
nective-tissue cells with their nuclei, on the other hand, become
more marked. The surface of the tunica propria contains
many slender papillae, which penetrate more or less deeply
into the epithelial covering. They have, also, the above-men-
tioned filamentous structure, but contain few cellular elements.

The transition of the tunica propria into submucous connec-
tive tissue is, in general, hardly perceptible. The latter, how-
ever, contains fewer elastic filaments and broader bundles of
connective tissue. The epithelium lining the buccal cavity is,
throughout, stratified pavement. The mucous membrane of
the mouth varies in different regions as to the thickness of its
different strata, the height of its papillae, and the condition of
the submucous tissue. It is thickest and firmest in the gums
and near the palate particularly in the posterior section of the
hard palate and thinnest in its reduplications, e.g., the froe-
num linguae, glosso-epiglottic fold, and the pillars of the fau-
ces. Its firmness in the above places is due to the density of
the submucosa, which forms, with the underlying periosteum,
one compact mass of connective tissue.



378 MANUAL OF HISTOLOGY.

Elsewhere the mucosa is looser, so that the mucous mem-
brane is readily thrown into folds. It is thickest wherever ifc
has intervening layers of glands. In some places, especially
in the lips and soft palate, the submucosa is crossed by bun-
dles of striped muscular fibres, which are connected partly
with the submucosa, and partly with the tunica propria. The
papillcz of the mucous membrane are most developed at the
margin of the lip and its immediate vicinity, as well as on the
gums, attaining here a height of 0.5 mm., and often termina-
ting in a double point. In the reduplications of the mucous
membrane (the fraenum linguae, etc.), and partly in the region
of the hard palate, the papillae are very small, sometimes rudi-
mentary. The thickness of the epithelial layer is proportion-
ate to the height of the papillae. Beginning at the vermilion
border of the lips, and going backward, the epithelial cov-
ering becomes progressively thicker, and is thickest at the
posterior margin of the lip, decreasing rapidly on the pos-
terior surface. Upon the cheeks and on the anterior surface
of the hard palate the epithelium is of medium thickness ;
it is thinnest on the floor of the mouth and on the above-
mentioned reduplications. There are, however, deviations in
these proportions, especially in the hard palate, where the
papillae are in some cases absent. Moreover, the tunica pro-
pria sometimes assumes an almost tendinous character. Cer-
tain important aggregations of glands, the so-called raucous
glandules, are found lodged in the submucous connective tis-
sue of the mouth. These are the labial, buccal, palatal, and
molar glandules. They are found as white, sharply denned
knobs, visible to the naked eye upon the posterior surface of
the lips, as well as upon the cheeks, palate, and bottom of the
buccal cavity. In some cases they are aggregated into a few
large clusters, while in others they are more scattered and
smaller. The orifices of their ducts are best seen in the lining
membrane by everting the lips or cheek. They belong to the
acinous type, and have a short duct, generally somewhat
curved, relatively wide, but somewhat contracted at the ori-
fice. The greatest width of the tubes is at their place of seg-
mentation. On the branches themselves are smaller ramifica-
tions, which either terminate directly with globular or ellipsoid
alveoli, or previously divide into one or more twigs. It often
happens that a small group of acini, with a narrow common



THE MOUTH AND TONGUE. 379

duct, situated near a larger duct, discharge into the latter near
the surface of the mucous membrane, appearing like a small
accessory glandule. The walls of the glandules consist of a
structureless basement-membrane, upon the interior surface of
which are superimposed cylindrical, clear, almost homogene-
ous-looking cells, with oblong nuclei.

As for the connection of the buccal mucous membrane with
the underlying structures, different conditions obtain in differ-
ent regions. Its connection with the hard palate and gums
has been described above. Where it is superimposed upon a
yliarply defined muscle, e.g., over the floor of the mouth, and
over the sublingual gland, it passes into the connective- tissue
sheath of the part.

The blood-vessels of the mucous membrane are arranged in
two systems of superficially extended networks. The deeper
one, located in the submucosa, is composed of the mutually
anastomosing branches of the afferent and efferent vessels.
From this network many smaller vessels penetrate into the
tunica propria, which, by division into still smaller branches,
and by frequent anastomoses with one another, form the more
superficial and finer-meshed vascular net. In both nets the
venous and arterial branches run tolerably parallel. From the
superficial network very fine branches enter the papillae, where,
according to their size, they form either capillary nets or sim-
ple loops.

The lymphatics form wide networks in the submucosa,
and narrow nets in the tunica propria. Single small vessels
cross those of the vascular nets. That lymphatics pene-
trate the papilla? is doubtful. The nerves of the buccal mu-
cous membrane form in the submucosa more or less dense
plexuses, in which many separations of the single nerve-fibrils
may be noticed. Thence numerous filaments, partly isolated,
partly arranged in small bundles, and always medullated,
ramify, and radiate in wider ramifications toward the super-
ficial layers of the mucous membrane. A certain number
of nerve-fibrils approach, the papillae, to implant themselves
either at their bases or at the centre of their apices, some-
times even at their extremities, in the terminal bulbs of
Krause. Such fibrils are most abundant in the lips and in the
anterior surface of the velum palati, and in smaller quantity in
the cheek and bottom of the mouth. Nerve-fibrils may some-



380 MANUAL OF HISTOLOGY.

times be seen also with double contours, which wind, during
their course, into a coil in the superficial layers of the mucous
membrane.



THE TONGUE.

Although the mucous membrane of the tongue is, in the
general details of its construction, similar to that of the rest of
the buccal cavity, it nevertheless presents some striking pecu-
liarities, mainly due to the configuration of its upper surface.
This is covered by many closely aggregated prominences of
the mucous membrane the lingual papillce which give it a
roughened, fungoid appearance. Upon the under surface of
the tongue the papillae are absent, but the mucous membrane
here contains a large number of follicular glands. The lateral
edges of the tongue are here and there covered with lingual pa-
pillae, which are often arranged in rows, and toward the base
of the tongue are replaced by the so-called fimbrice linguce.
Besides simple papillae, analogous to those of the skin, the lin-
gual mucosa is studded with three distinct varieties of com-
pound papillae the filiform, the fungiform, and the circum-
vallate. These are distinguished from the ordinary papillae of
the mucous membrane, not only by their large size and their
peculiar shapes, but also by their complicated structure, by the
arrangement of their secondary papillae, and the conditions of
their epithelial coverings. Between these three forms are
several intermediary ones. The filiform papillce are found all
over the dorsum of the tongue, anterior to the line of the cir-
cumvallate papillae. Not only in different individuals, but
also in the same tongue, there are marked variations in their
form. At the tip and lateral edges of the tongue they are
always smaller, and their filaments are wanting or merely ru-
dimentary. Toward the centre of the tongue they gradually
become larger and more abundant, and attain their highest
development in the angle made by the circumvallate papillae.

Their shape is that of a truncated cone, which has at its
free extremity a central hollow or depression, around which is
arranged, in a circular manner, a collection of thread-like pro-
jections, or secondary papillae. Like the rest of the mucous
membrane of the tongue, they are covered with stratified pave-
ment-epithelium. In the secondary papillae of the larger fili-



THE MOUTH AND TONGUE. 381

form papillae the epithelium is of the horny variety, and its
arrangement is imbricated, the lower margin of each scale over-
lapping the upper border of the scale next below it. In the
axes of the filiform papillae large-sized arterial and venous
capillaries extend. Each secondary papilla contains a vascu-
lar loop. The papillae of smallest size contain a fine network
of vessels, and in the posterior part of the tongue simple capil-
lary loops. Neither the filiform papillae nor their secondary
papillae contain nerve-fibrils. The latter are found, however,
at the base of the papillae, where they end in rounded terminal
bulbs.

The fungiform papillce are larger than the filiform, and
their epithelial covering is much thinner. They appear as
rounded prominences, somewhat constricted at the base, and
covered upon the sides and top with many cone-shaped second-
ary papillae. The free surface of some fungiform papillae is
smooth, the secondary papillae being farther apart. These are
found most commonly at the lateral edges of the tongue, and
are the so-called lenticular papillae. The distribution of the
fungiform papillae is rather irregular, and it varies in different
individuals. At the base of the tongue, and generally at its
lateral portions, between the filiform papillae, they are some-
times scarce and sometimes quite abundant. Toward the tip
of the tongue they are smaller, while they are larger in the
region of the circumvallate papillae. They are covered with
several layers of pavement-epithelium, the deeper strata of
which are formed by smaller polygonal prickle-cells. In this
epithelial covering, upon the surface of the fungiform papillae,
are constantly found peculiar bodies, called the " taste-goblets."

The taste-goblets vary in size and shape in different ani-
mals, and also in the same animal, according to the locality
in which they are found. They usually resemble a short-
necked flask, their longest diameter being the longitudinal.
The lower part of the taste-goblet rests upon the submucosa ;
the body, and more especially the part which corresponds to
the neck of the flask, is surrounded by epithelial cells. Every
taste-goblet has at the surface of the epithelium an opening
called aporus, which word is frequently used not only to des-
ignate the exterior opening, but also for the entire short canal
in the epithelial layer. The diameter of the porus is from
.0064 to .0198 mm. It is surrounded by two and sometimes by



382 MANUAL OF HISTOLOGY.

three similarly formed cells. Sometimes the poms is formed
by a single perforated cell. The short canal in the epithelial
cells is surrounded in like manner. In each taste-goblet two
varieties of cells may be distinguished the exterior or super-
ficial cells, called roof- or supporting-cells, and the interior, or
central cells, called taste- or rod-cells. The roof-cells, which
may be considered as modified epithelial cells, surround the
taste-goblets as petals envelop a bud. Their arrangement with
relation to one another is imbricated. The cells themselves
are long, narrow, spindle-shaped, arid curved, and each one
has a well-marked nucleus. The peripheral end of the cell is
pointed, while the central extremity is sometimes ramified.
The taste- or rod-cells are long, slender, and highly refractive.
A nucleus of unusual size almost entirely fills their bodies, while
their extremities pass into two distinct prolongations the pe-
ripheral or superior, and the central or inferior. The peripheral
prolongation is moderately broad, and has a short, del i< -ale
extremity, which resembles a small rod or hair. Hence ihe
name rod-cell. These rods are located inside the short canal,
and rarely project above the porus. The inferior prolongation
is divided into several rootlets. The connection of nerve-fila-
ments with the taste-goblets has never yet been conclusively
demonstrated, although all authorities agree as to the proba-
bility of such connection. Many aggregations of gangl ionic
cells, of greater or less size, are found in the course of the
nerve-bundles, near the circumvallate as well as near the fili-
form papilla). In the fungiform papilla) the nerves enter the
axis of the papilla) as small trunks, composed of fibres with
double contours. These divide into single nerve-filaments,
some of which terminate in bulbs, which are located in the lat-
eral surfaces of the fungiform papilla), under the secondary
papilhc. The fibrils which run into the axis pass into pale ter-