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successful injection of the hepatic
veins made by Harting ; it shows
ne irly the whole of two lobules, and
parts of three others : p, portal
branches running in the interlobular
spices ; h, hepatic veins radiating
from the centre of the lobules.

the accompanying bile-ducts ;
it is doubtful if they transmit
any blood directly to the capil-
lary network of the lobules.

The capillary network
of the lobules is very close,

so that commonly the interval between two vessels is not greater than the diameter
of two liver cells (figs. 153, 154, 155). Moreover, the vessels are comparatively
large (O'Ol mm.), and in specimens in which they have been filled with transparent
injection, can be seen, not only to pass in a radiating manner, as before described,
between the intra- and inter-lobular veins, but also in the human subject to be
continued from one lobule to another.

K 2




132 ORGANS OF DIGESTION.

The capillaries are accompanied by a small amount of fine connective tissue
of a retiform or reticular character, the fibrils of which are densely felted, and when
stained give the appearance of a close lattice-work. This is far better developed in
some animals than in man. Characteristic of this tissue is the presence of a large
number of stellate cells (Kupffer), which appear to be applied to the blood-capillaries.
This reticular tissue occurs more abundantly at the centre and surfaces of the
lobule, near the intralobular and interlobular veins, than elsewhere ; it forms a
delicate framework to the vascular and glandular structures. In the connective




Fig. 155. CROSS SECTION o? A LOBULE OF THE HUMAN LIVER, IN WHICH THE CAPILLARY NETWORK

< _ - BETWEEN THE PORTAL AND HEPATIC VEINS HAS BEEN FULLY INJECTED (from Sappey). (JU
DIAMETERS.

1, section of the intralobular or central vein ; 2, its smaller branches collecting blood from the
capillary network ; 3, interlobular or periplieric branches of the vena portse with their smaller
ramifications passing inwards towards the capillary network in the substance of the lobule.

tissue accompanying the interlobular veins there are numerous granular connective,
tissue cells.

The hepatic veins commence in the centre of each lobule by the convergence
of its capillaries into the single independent intralobular or central vein (figs.
153, h, and 155, 1), as already stated. These minute intralobular veins open at
once into the sides of the adjacent sublobular veins (fig. 153, s), which are of
various sizes, and join to form larger vessels, ending at length in hepatic venous
trunks, which receive no intralobular veins. Lastly, these, venous trunks, con-
verging towards the posterior surface of the liver, and receiving in their course other
sublobular veins, terminate in the vena cava inferior, as already described. In this
course the hepatic veins and their successive ramifications are unaccompanied by any
but lymphatic vessels. Their coats are thin ; the sublobular branches adhere
closely to the lobules, and even the larger trunks have but a slight areolar investment
connecting them to the substance of the liver. Hence, as already explained, the
divided ends of these veins are seen upon a section of the liver as simple open
orifices, the thin wall of the vein being surrounded closely by the solid substance of
the gland.

The hepatic cells. The interstices between the blood-vessels are, as before
said, almost entirely filled by the hepatic cells. These are of a compressed spheroidal
or polyhedral form, having a mean diameter of from O'OlTmm. to 0'022mrn. They
possess no cell membrane. Collectively they are yellowish, but, seen singly, are
colourless, with a variable numbsr of yellow or brown pigment granules in their



THE LIVER.



133



protoplasm. Their substance appears granular, and they contain each a clear round
nucleus, with intra-nuclear network and one or two nucleoli. Sometimes two
nuclei are to be found in a cell ; this is frequently the case in the rabbit. In many
cases, especially with a fatty diet, the cells are found to have large or small fat-
globules in their interior ; this fatty deposit is usually more abundant in the cells
which are near the periphery than in those near the centre of the lobule. When
isolated in the fresh condition they are said to exhibit slow changes of form. The
liver-cells are packed between and around the vessels, and in sections made at right
angles to the intralobular veins, appear as if radiating from the centre of the
lobules towards their circumference. They form a continuous network, or sponge-
work, the more obvious openings in which are the spaces occupied by the blood-
capillaries. The walls of the latter are not everywhere in contact with the liver




Fig. 156. HEPATIC CELLS FROM THE LIVER OF A DOG 14 HOURS AFTER A FCLL MEAL. (Heidenhain).

a, with glycogetiic deposit ; b and c, after its solution. In c the network of protonlasm which
remains is finer than in It, and imparts a somewhat granular appearance to the cells. The external
layer of the protoplasm contains no glycogen.

cells, but are separated from them in parts by a cleft-like lymphatic space, which is
only imperfectly marked off by the flattened and stellate connective tissue cells
before mentioned (p. 132).

The hepatic cells frequently contaiu glycogen, especially after a heavy meal of
starchy matters. It occurs in globules or in irregular amorphous masses within
them (Heidenhain), and when abundant reduces the protoplasm of the cell to
the condition of an open network, which becomes very distinct after solution of
the glycogen (fig. 15(5). When these masses of glycogen are not present the
protoplasm exhibits, after hardening, a more finely reticulated appearance (Klein,
Langley).

Commencement of the ducts. When a thin section of the hardened tissue is
examined under a high power of the microscope, minute apertures may occasionally
be observed between the opposed sides of adjacent liver-cells. These are the sections
of fine intercellular passages (lik-canaliculi), which form a close network (figs. 157,
158) between and around the individual cells, much finer and closer than the blood-
capillary network, from the branches of which they run apart. These passages are
the commencements of the biliary ducts, into which at the circumference of the
lobule they open. They may be injected from the trunk of the bile-duct, at
least in the outer parts of the lobule (fig. 157). It is uncertain whether they
have a proper wall, or if they are merely channels grooved out between the
hepatic cells.

To demonstrate the intercellular network throughout the whole extent of the
lobules, Chrzonszczewsky employed a method of natural injection. He introduced a
saturated watery solution of pure sulph-indigotate of soda, in repeated doses, into the
circulation of dogs and sucking-pigs, by the jugular vein ; and in an hour and



134



OKGANS OF DIGESTION.



a half afterwards the animals were killed, and the blood-vessels either washed out
with chloride of potassium, introduced by the portal vein, or were injected with
gelatine and carmine. In specimens prepared in this way the fine network of bile-
ducts throughout each lobule is filled with blue, while the intervening cells remain
free from colour. By killing the animals sooner after the injection, the blue
colouring matter was found within the hepatic cells, thus demonstrating that it was
through their agency that the canals were filled. They may also be shown by the
chromate of silver method.

From the observations of Pfliiger and of Kupffer, it would appear that the




Fig. 157. SECTION OF A LIVER-LOBULE WITH THE BLOOD-VESSELS AND DUCTS INJKOTED. (Cadiat. )

6, 6, interlobular veins ; a, intralobular vein ; c, interlobular bile-ducts, with which the bile
canaliculi from the lobule are connected. The canaliculi have only become injected in the peripheral
parts of the lobule.

relation between the hepatic cells and the bile-can aliculi is even more intimate than
has been generally supposed. For both by the methods of artificial and of natural
injection, they have demonstrated the existence of vacuoles within the cells
communicating by exceedingly minute intracellular channels with the adjoining
bile-canaliculi (see fig. 159). These observations have since been confirmed by
others, but it is not known whether the channels and vacuoles in question are
permanent structures, or whether they are only formed at the moment of secretion.

In the lower vertebrates and in the embryos of birds and' mammals the liver
is a tubular gland, composed of branching tubules nearly filled with the glandular
cells of the organ (fig. 160), and with narrow lumina (biliary canaliculi), directly



THE LIVER.



135



continuous with the ducts. The biliary canaliculi do not anastomose nor form a
network in the embryo (fig. 160), and in some mammals, e.g., mouse, Retzius was
unable to find evidence of a network, even in the adult state, althoUgfrin others

Fig. 158. SECTION OF RABBIT'S LIVER WITH THE INTER-
CELLULAR NETWORK OP BILE-CANALICULI INJECTED.

HIGHLY MAGNIFIED (Hering).

Two or three layers of cells are represented ; b, b,
blood capillaries.

(dog, man) it ia sufficiently obvious. In all
animals the bile-canaliculi are separated by
at least a portion of a liver-cell from the
nearest blood capillaries.

A different account of the structure of the
liver of the lower vertebrata and of the embryo
bird and mammal is given by Shore and Jones
(Journ. of Physiology, vol. x.).

Structure of the ducts. The minute
ramifications between the lobules have walls
composed of fibrillar connective tissue, within
which is a basement membrane, and a lining
of short columnar epithelium. According to
Heidenhain they also possess both longitudi-
nally and circularly disposed muscular cells

in their wall. As they pass into the lobules, the columnar epithelium becomes shorter
and flatter, the tube at the same time branching both laterally and terminally,
and becoming much reduced in size, so that only a very small lumen is left. The
basement membrane is no longer complete, and the intercellular bile passages open






Fig. 159. SKETCHES ILLUSTRATING THE MODE OF COMMENCEMENT OF THE BILE-CANALICULI WITHIN THE
LIVER-CELLS (Heidenhain after Kupffer).

A. Canalicnli of the rabbit's liver artificially injected from the hepatic duct with Berlin blue
solution. The intercellular canaliculi are seen to give off minute twigs, which penetrate into the liver-
cells, and there terminate in vacuole-like enlargements.

B. From a frog's liver naturally injected with sulph-indigotate of soda. A similar appearance is
obtained, but the communicating twigs are ramified.

directly into the minute ducts, the hepatic cells abutting against the flattened
epithelium of the latter.

In the portal canals, where they are somewhat larger, the ducts present numerous
openings on the inner surface, which are scattered irregularly in the larger ducts,
but in the*subdi visions are arranged in two longitudinal rows, one at each side of



ORGANS OF DIGESTION.



the vessel. These openings were formerly supposed to be the orifices of mucous
glands ; but, while the main ducts are studded with true mucous glands of lobulated
form and with minute orifices, the openings now referred to belong to saccular and
tubular recesses, which are often branched and anastomosing, and may be beset all
over with caecal projections (Theile). The larger bile-ducts have areolar coats, contain-
ing abundant elastic tissue, and a certain amount of plain muscular tissue disposed
both longitudinally and circularly. They are lined with columnar epithelium.

In the dnplicature of peritoneum forming the left lateral ligament of the liver,
and also in the two fibrous bauds which sometimes bridge over the fossa for the
vena cava and the fissure of the umbilical vein, there have been found biliary ducts
of considerable size which are not surrounded with lobules. These aberrant ducts,
as they are called, were described by Ferrein, and afterwards by Kiernan ; they
anastomose together in form of a network, and are accompanied by branches of the
vena portse, hepatic artery, and hepatic vein. They represent portions of hepatic

Fig. 160. FROM A CHROMATE OP

SILVER PREPARATION OF THE
LIVER OF A SIX MONTHS*

(Gr. Retzius.)




The bile-canaliculi are repre-
sented black. It is seen that at
this stage of development they do
not anastomose. They appear to
give minute offsets, which end
between and within the liver-
cells in small enlargements.

substance which were pre-
sent at an early period of
development, but have sub-
sequently become atrophied.
Lymphatics of the
liver. Lymphatics are
' seen in the prolongations
of G-lisson's capsule between the lobules (interlolular lymphatics), where they
accompany the blood-vessels, and in some cases surround and enclose them. They
originate from the lymphatic spaces around the capillaries of the lobules (p. 133).
They unite into larger vessels, which run along the portal canals (fig. 150, I /), and
emerge at the portal fissure. Other lymphatic vessels accompany the branches of the
hepatic veins, also conveying lymph from the peri vascular lymphatics of the lobules.
There is further a close subperitoneal plexus on the surface of the organ, which
on the upper surface communicates, through the ligaments of the liver, with the
thoracic lymphatics, and on the under surface with the lymphatics of Glisson's capsule.
In the pig's liver lymphoid follicles have been noticed by Kisselew and
Chrzonszczewsky, in connection with the interlobular lymphatics.

Nerves of the liver. The liver receives nervts from the left pneumogastric
and from the solar plexus of the sympathetic. The b: anches of the pueumogastric
reach the organ between the two layers of the small omentum and enter at the
portal fissure. The sympathetic branches also enter the portal fissure, accompanying
the hepatic artery : some branches also accompany the portal vein. The termi-
nations of the nerves within the liver have been investigated by Berkeley, who
describes them as ending in fine terminal arborizations, showing varicosities,
especially at their extreme endings, and as being distributed to the walls of
the blood-vessels and biliary ducts, and also between the hepatic cells of the
lobules. According to this author, they follow the course of the biliary canaliculi.
Korolkow has studied the nerve-endings in the liver of the pigeon by the methylene



THE LIVEfl.



137



blue method. He describes the nerves which enter the liver and accompany the
vessels and ducts to the intervals between the lobules as both medullated and non-
medullated. Of these, the latter are distributed almost exclusively to the arteries
and veins, whereas the former enter the lobules, and, losing their medullary sheath?,
run at first along the trabeculas of hepatic cells, and finally end by ramifying between
and over the cells (fig. 161).

Structure of the Gall-bladder. Besides the peritoneal investment and the
mucous lining, the gall-bladder possesses an intermediate muscular and connective
tissue coat, of considerable strength. This consists mainly of bands of dense shining
white fibres, which interlace in all directions. Intermingled with these are plain



a




Fig. 161. PLEXUS ov NERVE-FIBRILS WITHIN A HEPATIC I.ODULE OF THE PIGEON ; METHYLENE CLUE

METHOD. (Korolkow.)

a a, axis-cylinders of nerve-fibres, passing between the cell-trabeculie of the lobule, c ; b b, fibrils
ramify ing over the cells of the trabeculye.

muscular fibres, which have principally a longitudinal direction, but some run
transversely. This coat forms the framework of the organ, and supports the larger
blood-vessels and lymphatics. The nerves form a gangliated plexus within it ;
partly also immediately beneath the serous coat (L. Gcrlach).

The mucous membrane which after death is generally strongly tinged with bile,
is elevated upon its inner surface into very numerous small ridges, which, uniting
together into meshes, leave between them depressions of different sizes, and of various
polygonal forms. This gives the interior of the gall-bladder an alveolar aspect,
similar to what is seen on a smaller scale in the vesicular seminales. These alveolar
intervals become smaller towards the fundus and neck of the gall-bladder, and at the
bottom of the larger ones other minute depressions, which may be seen with a simple
lens, lead into numerous mucous recesses. The whole of the mucous membrane is
covered by columnar epithelium, and it secretes an abundance of viscid mucus.
The blood-vessels form a close network near the surface of the mucous membrane,
and there is also a fine lymphatic plexus in the mucous membrane, communicating
with a network of larger vessels in ihe serous coat.



ORGANS OF DIGESTION.

At the places where the neck of the gall-bladder curves on itself there are strong
folds of its mucous and areolar coats projecting into the interior.

In the cystic duct the mucous membrane is elevated internally in a similar
manner into a series of crescentic folds, which are arranged in an oblique direction,
and succeed closely to each other, so as to present very much the appearance of a
continuous spiral valve. When distended, the outer surface of the duct appears to
be indented in the situation of these folds, and dilated or swollen in the intervals
so as to present an irregularly sacculated or twisted appearance. In the structure of
its wall the cystic duct resembles the gall-bladder.

RECENT LITERATURE OF THE LIVER.

Berkley, Henry J., Studies in the histology of the liver. 1. The intrinsic nerves, Anat.
Anzeiger, Jg. viii., 1893.

Braum, H. , Die morphologisck-histologischen Verdnderungen in den ruhenden und thdtiycn
Lcberzellen, Deutsche Zeitschr. fiir Tiermedicin, Band xii., 1886.

Brunton, T. Lauder and Delepine, Sheridan, On some of the variations observed in the
rabbit's liver under certain physiological and patholjgical circumstances, Proc. of the Roy. Soc.,
vol. I., 1892.

Cavassani, E., Ueber die Verdnderungen der LeberztUen icahrend der Reizung d. Plex,
ca'liacus, Arch. f. d. gesammte Physiologic, Bd. Ivii., 1894.

Cunningham, D. J., Delimitation of the regions of the abdomen. Part II., Topography of
the viscera. Jour. Anat. and Phys., vol. xxvii., 1893.

Delepine, S. , Contribution to the study of the vertebrate liver, Proceed, of the Roy. Soc., 1891,
vol. xlix.

Disse, J.. Ueber die Lymphbahnen der Saugetierleber, Archiv f. mikroskop. Anat., Bd. xxxvi.,
1890.

Faure, J. L. , L'apparcil suspenseur du foie, &c. ; Quelques points de I'anatomic du canal
cystigue, Bull, soc, anat., Paris, 18y2.

Frenkel, Moise, Du tissu conjonctif dans le lobule hepatiquc de certains mammi feres, Comptes
rendus hebdom. de la soc. de biol., 1892.

Gebergr, A., Ueber die Gallengdnge in der Saugetierleber, Internat. Monatsschr. f. Anat. u. Physiol.,
Bd. x., 1893.

Hartmann, H., Quelques points de Vanatomie et de la chirurgie des votes biliaircs, Bull, soc
anat., Paris, 1891.

Hertz, P., Abnormitdtcn in der Lage und Form der Bauchorgane, 1894.

Hoeppe, H.. Muskeln und Klappen in den Wurzeln der Pfortadcr, Archiv f. Anat. u. Physiol.,
Jahrg. 1890, Physiolog. Abt., Supplement Band.

Korolkow, P., Ueber die Nervenendigungen in der Leber, Anat. Anzeiger, Jahrg. viii., 1893.

Kraiise. Rudolf, Beitrdge znr Histologie der Wirbcltierlcber, Arch. f. mikrosk.Anat. , Bd. xlii.,
1893.

Lahousse, E., Contribution d I'etudc des modifications morphologiqucs de la cellule hepatiquc
pendant la secretion, Archives de biologic, tome vii., 1887.

Landau, Die Wdnderleber und die Hdngebauch der FraUen, 1885.

Macallum, A. B., The termination of nerves in the liver, Quarterly Journ. of Microscop.
Science, vol. xxiv., 1887.

Mall, F., Das reticulirte Gewebe u. seine Bezichungen z. d. Bindcgewebsfibritten, Abhandl. d.
k. Sachs. (JeseUsch., xvii., 1891.

Oppel, Albert, Ueber Gitterfascrn der menschlichen Leber und MHz, Anatom. Auz., Jahrg. vi.,
1891.

Pilliet, A., Contribution d V etude des espaces portes du foie chez quelques vertebras, Journ. de
1'anatoniie, annee xxv. , 1889.

Retzius, Gustav, Ueber die Gattenkapittaren und den -Driisenbau der Leber, Biol. Unter-
suchungen, N. F., Bd. iii., 1891, and iv., 1892.

Rex, H., Beitrdge zur Morphologic der Sdugerlcber, Morphol. Jahrbuch, Bd. xiv., 1888.

Rolleston, H. D., Abnormal vascular supply to the liver, Journ. of Anat. and Physiol.,
vol. xxiv., 1889 ; Specimens of livers with aiwmaiies in their lobulation, Pr. Anat. Soc. Gt. Brit, and
Ireland, Journ. Anat. and Phy.siol., vol. xxvii., 1893.

Sabourin, Ch., Recherches sur I'anatomie normale et pathologique de la glande biliaire de
I'hommc, Paris, 1888.

Shore, Thomas W., Notes on the origin of the liver, Journ. of Anat. and Physiol., vol. xxv., 1891.

Shore, T. W., and Jones, H. L., On the structure of the vertebrate liver, Journ. of
Physiol., vol. x., 1889.

Stocquart, Alfr., Note sur le poids et des dimensions dufoie chez I 'enfant, Internat. Monatsschr.
f. Anat. u. Physiol., Bd. viii., 1891.

Symington, Johnson, On certain physiological variations in the shape and position of the liver,
Edinburgh Med. Journ., Feb., 1888.

Thomson, A., Some variations in the anatomy of the human liver, Journ. Anat. and Phys.,
vol. xix., pt. iii., 1885.



THE PANCREAS.



139



THE PANCREAS.

The pancreas (fig. 162) is a long gland of a reddish cream colour and
irregularly prismatic shape, which lies across the posterior wall of the abdomen,
behind the stomach, and opposite the first and second lumbar vertebrae. Its right
end is the larger and is termed the head ; from this arises a short and slightly con-
stricted neclc, which connects the head with the lody. The body passes to the left,
its free extremity or tail touching the spleen.

The pancreas varies considerably, in different cases, in its size and weight. It is usually
5 or 6 inches (120 150 mm.) long, and from half an inch to an inch in thickness. The




Fig. 162. ANTERIOR ASPKCT OP THE PANCRF.AS, &c., DRAWN BY GK G. R. HARBINSON, FROM A SPECIMEN

PREPARED BY HARDENING THE ABDOMINAL VIS3ERA IN SITU BY THE INJECTION OF A 1 P.O.
SOLUTION OF CHROMIC ACID. (J. S.)

H.H.H., head of pancreas ; C. . its neck ; B.B. , its body ; A., anterior surface of the body ; I., its
inferior surface ; O.T., omental tuberosity near right end of body ; 2nd, 3rd, 4th, corresponding parts of
the duodenum ; J. , jejunum ; H. A., hepatic artery; Gr., gastric artery ; S.P., splenic artery; (I.D.,
gastro-duodenal artery ; S.P.D., superior pancreatico-duodcnal artery ; S.V., splenic vein ; I.M.,
inferior mesenteric vein ; S.M.Y., superior mesenteric vein ; P.V. , portal vein ; B.I)., bile duct.

weight of the gland, according to Krause and Clendenning, is usually from 2^ to 3^ oz. (G(i to
102 grammes) ; but Meckel has noted it as high as 6 oz., and Soemmerring as low as 1^ oz.
Its specific gravity is 1'046.

The head (fig. 102, H) of the pancreas forms a disc-shaped mass flattened from
before backwards, and lying in the concavity formed by the second, third, and fourth
parts of the duodenum, to which it is closely united. The superior mesenteric
vessels are in contact with the anterior surface near its left border, while near its
lower end it is crossed by the transverse colon and its meso-colon. The superior
and inferior pancreatico-duodenal vessels pass down in front of the head a short



140



ORGANS OF DIGESTION.



distance from its right and left borders respectively. Posteriorly it lies upon the
inferior vena cava, the left renal vein and the aorta. The common bile duct
passes down behind it, and is generally received into a groove or canal in its
substance.

The necleof the pancreas (fig. 162, C) is about an inch long. It springs from the
upper part of the anterior surface of the head and turns upwards, forwards, and to
the left to join the body. In its course it passes in front of the termination of the
superior mesenteric vein and the commencement of the vena portse. At its attach-
ment to the head it is grooved on its right side by the gastro-duodenal and superior
pancreatico-duodenal arteries. The first part of the duodenum lies against its




Fig. 163. VIEW OF THE ABDOMINAL VISCERA FROM BEHIND, AFTER REMOVAL OF THE SPINAL COLUSIX,

THE WHOLE OF THE POSTERIOR WALL OF THE ABDOMEN AND THE KIDNEYS AND SUPRA-RENAL

CAPSULES, THE PERITONEUM BEING LEFT (this and the next figure are taken from Prof. His'

models). ^

P, pancreas ; f, its head ; d, duodenum ; st, stomach ; spl, spleen ; R.L., right lobe of the liver ;
L.K., Spigelian lobe ; v.c.i., vena cava inferior ; p.r., portal vein ; b, common bile duct ; i.r., impres-



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