mucous plug, which fills the canal of the cervix during preg-
nancy. Subsequent to delivery a new mucous membrane and
glands are developed on the cavity of the uterus, and the hy-



240 MANUAL OF HISTOLOGY.

pertropliied and newly formed muscular elements undergo
retrograde development and fatty metamorphosis.

The Fallopian tubes, or temporary ducts of the ovary, con-
sist of an external covering furnished by the peritoneum, rich
in connective tissue and blood-vessels ; a muscular coat made
up of an outside layer of longitudinal, and an inside layer of
circular involuntary muscular elements ; and, finally, an in-
ternal mucous membrane. A division of the tube is made into
two parts: that toward the uterus, into which it opens, the
much narrower portion, is the isthmus, while the free half is
the ampulla, which terminates in the fimbrice. The mucous
membrane, upon transverse section of the tube, in the narrow
portion, is seen thrown into simple longitudinal folds, while in
the ampulla the folds are much more complicated, and in a
transverse section have a dendritic appearance. The epithelium
covering the mucous membrane consists of ciliated columnar
epithelial cells. The movements of the cilia occasion a current
in the direction of the uterine opening. There is an absence of
glands in the mucous membrane of the Fallopian tubes. The
same histological elements are present in the fimbrise as in
other portions of the tube, of which they are a direct contin-
uation.

The ovary for histological study may be divided into two
parts, the cortex and medullary substance ; covering the cor-
tex is a layer of columnar epithelial cells, named the ovarian
or germ epithelium (Fig. 107). In a perpendicular section, the
germ-epithelium is here and there seen to extend down into
the substance of the organ and form tubes the ovarial tubes.
The cortical substance or parenchymal zone consists of several
layers of dense connective tissue, in which are found ovarial
tubes and ovarian follicles. The most external follicles are im-
perfectly developed, while those lying deeper are more highly
developed and contain the ovum. Internal to the cortex is the
medullary substance or vascular zone, in which are numerous
blood-vessels, giving it the nature of a cavernous tissue.

The stroma of the ovary consists of fibrillar connective tis-
sue. In the vascular zone it is somewhat loose in texture, and
contains a network of elastic tissue. There are also found in
this zone fasciculi of smooth muscular fibres, which follow the



THE FEMALE ORGANS OF GENERATION.



247



large and medium sized arteries, afc times constituting a sheath
for the vessels. In the stroma of the parenchymal zone the
connective- tissue forms an outer layer of short, dense fibres




FIG. 107. From the ovarium of a rather old bitch ; portion of a sagittal section, a, germ-epithelium ;
ft, &, ovarial tubes ; c, c, younger follicles ; d, older follicle ; e, discus prollgerus, with egg ; /, epithelium
of a second egg in the same follicle ; flf, tunica fibrosa folliculi ; A, tunica propria folliculi ; i, follicular
epithelium (membrana granulosa); , collapsed, degenerated follicle; f, vessels: TO, TO, cell-tubes of the
parovarium, both longitudinal and transverse sections ; j/. tubular sinking in of the germ-epithelium into
the substance of the ovary ; , commencement of the germ- epithelium close to the lower border of the
ovary. Waldeyer.



which run in every direction, and an inner one abounding in
cells, in which the follicles are seen.

The blood-vessels enter the ovary at the hilum. The arteries
have a spiral, corkscrew-like course through the organ. At
the hilum the veins form a convoluted mass, the bulb of the



248 MANUAL OF HISTOLOGY.

ovary. A capillary reticulum surrounds tlie follicles, and is
situated in their internal membrane.

The stroma of the hilum contains numerous lymphatics,
which have an arrangement similar to that of the veins. Sur-
rounding the follicles in their external lamina is found a dense
network of lymphatics.

The nerves enter the ovary at the hilum with the arteries,
and they have been followed into the stroma between the large
follicles, but their ultimate terminations have not as yet been
ascertained.

The follicles of the ovary, or Graqfian follicles, consist of a
connective-tissue wall separable into two layers : an internal,
which contains the small capillaries, and an external, contain-
ing the large blood-vessels and lymphatics. The outer layer is
made up of the same connective tissue as the stroma of the
ovary, in which are numerous spindle-shaped cells. The inter-
nal layer consists of connective tissue, in which are numerous
and variously shaped cells, fusiform, stellate, and small round
bodies, the latter possessing amoeboid movement ; there are
also seen larger round or polygonal-shaped cells. This layer of
corpuscles is the membrana granulosa. Within the follicle,
and distending it, is an albuminous fluid holding a few bodies
in suspension. Situated in the follicle, usually at that part
most distant from the surface of the ovary although this is
not a rule without exception, since it is also found immediately
below the most superficial part of the follicle the ovum is
found surrounded by a collection of cells of the granular mem-
brane, known as the discus proligerus. Two kinds of cells
form the discus proligerus, the follicular and egg epithelium ;
the latter lie in immediate contact with the vitelline membrane,
and are closely adherent to it.

An examination of the mature ovum demonstrates it to
measure 0.28 to 0.1379 mm. in diameter ; it is spherical in
shape, and is a typical cell, consisting of an investing mem-
brane, the vitelline membrane, or zona pellucida, which is
a dense, transparent, homogeneous substance, apparently
pierced by numerous minute pores. This membrane is prob-
ably developed from the cells of the discus proligerus, and from
the layer described as the egg epithelium. The cell-contents,
protoplasm, or vitellus is a granular mass composed of albu-
minous and fatty particles, and a more or less distinct reticu-



THE FEMALE ORGANS OF GENERATION.



249



lum of fine fibrils. Within the vitellus is seen the nucleus or
germinal vesicle (also presenting a delicate reticulum of fibrils),
situated eccentrically, spherical in shape, measures 0.037 to
0.451 mm. in diameter, shining, transparent, and contains the
nucleolus or germinal spot, which is a highly refractile body,
finely granular, supposed to be non-vesicular, and measures
0.0046 to 0.0068 mm. in diameter.

The mature Gfraafian follicle, which is seen on the surface




FIG. 108. 4, primordial egg of the human being ; 8 months 1 fcetus. B, primordial follicle of the
rabbit. <7, primordial follicle of a dove. D, a somewhat older follicle of the same animal ; commence-
ment of the formation of the subordinate yolk. E, blind end of the ovary of an ascaris nigrovenosa ;
germinal vesicles (some of which possess a germinal spot and Schron's ''granule") in a diffuse mass of
protoplasm. F, egg of the ascaris nigrovenosa from about the middle of the ovary ; Schron's granule ;
commencement of the deposition of yolk-matter. <?, egg from a follicle (2 mm. in diam.) of the rabbit :
a. egg-epithelium; &, striated zone with radiating striae ; c, germinal vesicle; d, germinal spot ; e, yolk.

of the ovary, giving rise to a prominence, ruptures during the
menstrual period and empties its contents, viz. : the ovum,
fluid contents, and discus proligerus into the Fallopian tube.
The cause of the rupture is an increase in the contents of the
follicle, and a fatty metamorphosis of the cells of the wall of
the follicle. As a result of this rupture of the Gfraafian vesi-
cle, there is formed a yellow body, the corpus luteum, which



250 MANUAL OF HISTOLOGY.

reaches its full development in a few weeks after the raptur-
ing of the follicle, or when impregnation has occurred after the
lapse of two or three months. It consists of a central portion,
at first red, becoming gray, and a peripheral portion, yellow in
color, thrown into folds. These folds are made up of the in-
ternal membrane and cells. The central portion in a fresh
corpus luteum consists of a very vascular tissue, in which are
seen numerous large cells, containing a red coloring substance
and hsematoidin crystals. A retrograde metamorphosis occurs
in the yellow body, supposed to be due to a want of nutrition
caused by a wasting of the arteries, and there only remains a
white cicatrix, the corpus albicans. The time required for
the disappearance of a corpus luteum when impregnation has
taken place a true corpus luteum is several months, lasting
to the end of gestation ; but for the disappearance of a false
corpus luteum, or when impregnation has not occurred, it only
requires a few weeks. It is, however, to be remembered, that
every Graafian follicle with its contents does not reach full de-
velopment ; most of them experience fatty or colloid metamor-
phosis.

The ovaries have their origin from the Wolffian bodies. A
thickening of the epithelial covering is early observed upon
the side of these bodies ; at the same time and place a cellular
projection growing from the connective tissue of the organ is
noticed. From this increase of epithelium the Graafian folli-
cles and ova are developed, later the ovarial epithelium ; from
the connective tissue is built up the vascular system of the ovary.

The Graafian follicles are developed from collections of cells,
irregular in shape, or, as they are named, ova chains, consisting
of small-sized peripheral cells, which later form the membrana
granulosa, and the primordial ova ; these last are recognized
by their large size, granular or reticulated protoplasm and
central position. The ova chains are sometimes enclosed in a
homogeneous membrana propria, forming a tubular structure,
as in the cat ; this membrane, however, is not found in all ani-
mals. These chains are developed by an ingrowth of the epi-
thelial cells covering the surface of the ovary.

The parovarium, or remains of the Wolffian body, situated
in the broad ligament, is made up of twelve to fifteen tubules,
which possess a membrana propria, lined by a single layer of
ciliated epithelium, and contain a transparent substance.



THE FEMALE ORGANS OF GENERATION. 251

The placenta is divided into a uterine and foetal portion.
The former consists of cells irregular in shape, containing one
or several nuclei, and at times one or more nucleoli. These
cells are separated by an intercellular substance, either hyaline,
granular, or fibrous in nature. Fusiform cells, in which a rod-
shaped nucleus is seen, are also found, and are thought to in-
dicate the presence of smooth muscular elements. The tufts
upon the surface of the uterine placenta, which divide and sub-
divide, pass quite deeply into the foetal placenta, yet no direct
transformation of them into the foetal tissue can be demon-
strated ; they appear to terminate in fibrillated tissue, which
contains none of the cellular elements of the uterine placenta.

The blood-vessels of the uterine placenta are arteries and
veins, with no intermediary capillary system ; they communi-
cate by means of sinuous spaces, limited by placental tissue
only. These spaces are said to possess a delicate limiting wall ;
this statement, however, has not been confirmed.

The foetal placenta is developed from the chorion, the villi
or tufts of which growing into the uterine follicles are covered
by a columnar epithelium. The blood-vessels in the villi do
not lie directly in contact with the wall of the villus, but are
separated from it by a perivascular space. Besides a direct
communication of the arteries and veins, there is also a capil-
lary system present in the villi. Connective tissue accompa-
nies the vessels into the villi from the chorion. The variety of
connective tissue here met with is the mucoid, consisting of
round, spindle, and stellate-shaped cells, with a structureless
intercellular substance. There is a direct transformation of
this mucoid connective tissue into the connective tissue of the
chorion.



BIBLIOGRAPHY.

BISCIIOFF. Beitr. zur Lebre v. d. menschl. EihtLllen. 1834.

VALENTIN, in Muller's Arch., p. 526. 1838.

GOODSIR. Anat. and Path. Researches. Edinburgh, 1845.

KOBELT. Der Nebeneierstock des Weibes. Heidelberg, 1847.

STEINHN. Ueber d. Entw. d. Graaf. Foil. u. Eier d. Saugeth., Mittheil. d. ZU-

richer naturf. Gesellsch. 1847.
ROBIN. Arch, gener. de med. Vol. XVII., p. 258 and 405. 1848. And Vol.

XVIII., p. 257. Also Gaz. med. No. 50. 1855.
BAINEY, in Phil. Trans., II. 1850.



252 MANUAL OF HISTOLOGY.

SCHRODER VAN DER KOLK. Waarnemingen oves liet Maaksel van de menschl.

Placenta, etc. Amsterdam, 1851.

SMITH, TYLER-. Med. Chir. Trans. Vol. XXXV., 378. 1852.
KEMAK. Unters. ueb. d. Entwick. d. Wirbelthiere. Berlin, 1855. Med. Centr.

Zeit. No. 42. 1861. No. 3. 1862.
KLEBS, in Virch. Arch. Vol. XXVIII. 1863.

PPLUGER, E. Ueb. d. Eierstocke d. Saugeth. u. d. Menschen. Leipzig, 1863.
SPIEGELBERG. Virch. Arch. Vol. XXX , p. 466. 1864.
KAMENEW. Unters. d. Blutgef. d. Mutterth. d. Placenta, Medicinsky Westnik.

No. 13. 1864.
CORNIL, in Jour, de 1'anat., p. 386. 1864. Unters. aus d. phys. Labor, zu Bonn,

p. 173. Berlin, 1865.

POLLE. Die Nerveuverbr. in d. weibl. Genital. Gottingen, 1865.
His, in Arch. f. mikr. Anat. Vol. I., p. 151. 1865.

ST. GEORGE, v. LA VALETTE, in Arch. f. mikr. Anat. Vol. II., p. 56. 1866.
PERIER. Anat. et phys. de Fovaire. Paris, 1866.
STRICKER. Wien. Sitz. June, 1866.

LANGHANS, in Virch. Arch. Vol. XXXVIII., p. 543. 1867.
FRANKENHAUSER. Die Nerven. d. Gebarmutter. Jena, 1867.
JASSINSKL Zur Lehre ueb. d. Struct, d. Placenta. Virch. Arch. 1867.
VIRCHOW. Bildg. d. Placenta, in Gesamm. Abhandlungen. 1853.
BIDDER. Ueb. Hist. d. Nachgeb., in Hoist's Beitr. z. Gynacol. II. 1867.
ERCOLANI. Giamb. delle gland, otricolare, etc. Bologna, 1868.
PLIKOL, in Arch. f. mikr. Anat. VoL V., p. 445. 1869.
FRIEDLANDER. Unters. ueb. d. Uterus. 1870.
HENNIG. Der Catarrh d. inn. weibl. Geschlechtsorg. 1870.
WALDEYER. Eierstock. u. Ei. Leipzig, 1870.
LOTT and A. ROLLET. Untersuchungen. II. Leipzig, 1871.
LANGHANS. Unters. ueber d. menschl. Placenta. Arch. f. Anat. u. Phys. 1877.
LEOPOLD. Stud. ueb. d. Uterus-schleimhaut. Arch. f. Gyn. Vol. XI., p. 110 and

443. 1877. Also Vol. XII., p. 169. 1877.

HENNIG. Ueber Driisen der Vagina. Arch. f. Gyn. Vol. XII., p. 488. 1877.
FOULIS. The Development of the Ova, and the Structure of the Ovary, etc. Jour.

of Anat. and Phys. Vol. XIII., p. 353. 1878-79.
FREY, HEINRICH. Histology and Histochemistry of Man. 1880.
KLEIN, E., and E. NOBLE SMITH. Atlas of Histology. 1880.



CHAPTER XVII.

THE BESPIBATOBY TBACT.

BY BENJAMIN F. WESTBROOK, M.D.,

Lecturer on Anatomy and Pathological Anatomy at the Long Island College Hospital,

Brooklyn, N. Y.

THE respiratory tract includes the nares and, perhaps, the
pharynx, but as the latter is more commonly associated with
the function of deglutition, and the former contain in their
tipper portions the organs of one of the special senses, they
have been assigned to other portions of this work. This chap-
ter is devoted exclusively to the consideration of those parts
which are concerned in the respiratory process. As the pleura
forms a part of the lung, and facilitates the movements of
breathing, its structure may properly be described under this
section.

The air-tubes are in general made up of three layers : an
outer of connective tissue and elastic fibres ; a middle, muscu-
lar and cartilaginous; and an inner of mucous membrane.
Their structure is more complex in the upper, and simpler in
the lower portions of the respiratory passages.

The larynx. The muscles of the larynx are of the striped
or voluntary variety.

The ligaments and membranes are composed of yellow elas-
tic fibres with some white fibrous tissue. Their structure can be
easily demonstrated by the process of teasing or by employing
the reagents ordinarily used for this class of tissues. The la-
teral thyro-hyoid and the inferior thyro-arytenoid ligaments
have the following peculiarities of structure : the lateral thyro-
hyoid ligament usually encloses a small piece of hyaline carti-
lage about the size and shape of a large grain of wheat. It
is known as the cartilago triticea. In adult males it is usually
calcified. It may be incorporated either with the cornu of the
hyoid bone or with the superior cornu of the thyroid cartilage.






254 MANUAL OF HISTOLOGY.

The inferior thyro-arytenoid ligaments, or true weal cords,
are made up almost entirely of yellow elastic fibres stretched
across from the thyroid cartilage in front, to the vocal processes
and adjacent anterior borders of the arytenoids behind. The
elastic bundles originate, anteriorly, in a mass of connective
tissue which occupies the angle of the thyroid. Posteriorly,
many of the fibres are prolonged into the arytenoid cartilage,
converting that part of it into reticular tissue. These liga-
ments are continuous below with the lateral crico-thyroid mem-
branes, and are described by some anatomists ' as their superior
borders.

The innermost fibres of the internal thyro-arytenoid mus-
cle mingle with the outer fibres of this ligament, some ending
in or taking their origin from them. The intimate relation be-
tween the muscle and the ligament can be seen in a vertical sec-
tion through the larynx.

Of the laryngeal cartilages, the three larger are of the
hyaline variety. Horizontal sections show a broad central area
with two zones between it and either the outer or inner sur-
face. The appearance of the zones or bands is thus described
by Rheiner : a " 1. A thin peripheral portion, appearing to the
naked eye as a narrow, bluish, opalescent band, which con-
sists of a transparent and longitudinally striated matrix with
elongated cartilage- cells arranged parallel to the surface. 2.
The intermediate layer, a narrow, whitish, opaque band, con-
sisting of a dull yellowish ground-substance with numerous
large mother-cells containing fatty daughter-cells. 3. The
broad central layer, with a perfectly transparent homogeneous
matrix and few cells. The intercellular substance increases,
relatively to the contained cells, from without inward, and, in
the interior, presents numerous large spaces in which no cells
are found. In the thyroid and cricoid cartilages the outer
peripheral zone is thicker arid more easily distinguished than
the inner."

The following peculiarities are to be noted : the central por-
tion of the thyroid, viz., that part which forms the anterior
projection or angle, is distinguished by the great number and
small size of its cells. It is penetrated by numerous fibres

1 Quain's Anatomy, eighth edition, Vol. II. , p. 284.

2 Quoted by Merkel in Anatomic u. Phys. des mensch. Stimm- u. Sprach-Organs.
Leipzig, 1863, S. 166.



THE RESPIRATORY TRACT. 255

from that mass of connective tissue from which the vocal cords
take their origin. After prolonged maceration in some alka-
line solution, this cartilage can be separated into three parts
two lateral and an anterior or median.

The arytenoids are not composed exclusively of hyaline
cartilage. The vocal process, as already mentioned, presents a
yellow reticulated structure, the fibres of which are continuous
with those of the true vocal cords. The apex has also a re-
ticular structure when there is no joint between it and the
cartilage of Santorini. The elastic tissue is then continuous
with that which connects it with the corniculum. A hori-
zontal section through the arytenoid at the level of the vocal
process shows the reticular structure of the process, the hya-
line character of the body of the cartilage, and the gradual
transition from one to the other.

The three cartilages already described are subject to calci-
fication and partial ossification. This occurs more frequently
and at an earlier age in the male than in the female. It also
begins at a later date in those who have been castrated. It
makes its first appearance at the points of muscular attach-
ment. As the cartilages undergo calcification they increase in
size, so that the calcified larynx of old age is larger than that
of the young adult. The matrix also splits up into a fibrous
texture, not affected by acetic acid.

The cornicula laryngis or cartilages of Santorini and the
cuneiform cartilages of Wrisberg, as well as the sesamoid
cartilages (when they exist) are of the reticulated variety.
The cartilago triticea is hyaline and prone to calcification.

The epiglottis consists of reticular cartilage. On transverse
section, however, the intercellular substance is seen to be a
spongy elastic substance, granular on section ; at the periphery
yellow fibres are present. The elastic cartilage should be ex-
amined with a high power.

The mucous membrane of the larynx varies in its structure
in different situations. On the laryngeal surface of the epi-
glottis it is thin.

The epithelium in the upper half is in several layers. The
deepest cells are somewhat columnar or pyramidal in form,
while the superficial ones are flat. The lower half is covered by
a stratified, columnar, ciliated epithelium. The epithelium rests
upon a thin, apparently structureless basement-membrane.



256 MANUAL OF HISTOLOGY.

The nmcosa is made up of delicate connective-tissue fibres, en-
closing in their meshes a series of lymph-spaces. Connective-
tissue cells are also found here, and some elastic fibres. There
are a few small papillae in the upper portion. The submucous
layer is thin, contains many elastic fibres, and is continuous
with the perichondrium. It contains the racemose mucous
glands, whose ducts open upon the surface. Some of the larger
glands are lodged in the depressions of the cartilage, and some
are even situated on its anterior aspects, their ducts passing
through to the posterior side.

In the submucous tissue there are lymphatic follicles, some
of which are arranged about the mucous glands and their ducts.

The membrane covering the false vocal cords, arytenoid
cartilages, and ary-epiglottic folds, as well as that lining the
ventricles and inferior compartment of the larynx is thicker
and more loosely attached to the subjacent parts. It is covered
by stratified columnar, ciliated epithelium, except upon the
edge of the false vocal cords and over the inner surfaces of the
arytenoids, where it is of the pavement variety. The mucosa
contains a large amount of lymphoid tissue, which holds in its
meshes lymphoid cells. Closed lymph-follicles are also found
in the submucous tissue of the false vocal cords and on the
floor of the ventricle. 1 That portion of the mucous membrane
which covers the true vocal cords is thin, more closely attached,
and has no mucous glands. In its anterior half it has numer-
ous small papillae (0.07 to 0.08 mm. in height, Coyne) project-
ing at the edge and on the superior and inferior surfaces of the
cord. They are composed of connective tissue, with many elas-
tic fibres. Their vascular supply is slight. The membrane in
this situation is covered by stratified pavement -epithelium,
continuous posteriorly with that which covers the inner sur-
faces of the arytenoids. Numerous racemose glands send their
ducts obliquely upward and inward to discharge their secretion
upon the upper and under surfaces of the vocal cords.

In front of the corniculum laryngis, on either side, is a col-
lection of racemose glands surrounding the cartilage of Wris-
berg. Another collection is found between the arytenoids.

The epithelium can be examined, either by scraping it from
the surface, or in sections. The mucous glands are best seen

1 Coyne : Archiv. d. Physiologie, p. 92, 1874.



THE RESPIRATORY TRACT. 257

in sections of the hardened larynx. They are lined by cubical
glandular epithelium. The capillary blood-vessels of the laryn-
geal mucous membrane are small with wide meshes, giving the
membrane a paler appearance than that of the pharynx.

The lymphatics are numerous in the mucous and sub-
mucous layers. They may be injected with Berlin blue, by
puncturing the submucous tissue.

In the nervous filaments are ganglion cells. The mode of
termination is not definitely known. But in the mucous
membrane of the epiglottis end bulbs have been found. The
methods of examination will be found elsewhere.

The trachea and primary bronclii. The rings of the trachea
and bronchi are composed of hyaline cartilage. Longitudinal
sections of these rings show that the cells lying near the peri-