Difference between revisions of "Paper - The lobule of the spleen (1898)"

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=The Lobule of the Spleen=
 
=The Lobule of the Spleen=
 
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[[File:Franklin Mall 01.jpg|thumb|150px|alt=Franklin Mall (1911)|link=Embryology History - Franklin Mall|Franklin Mall]]
 
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By [[Embryology History - Franklin Mall|Franklin P. Mall]].
By Franklin P. Mall.  
 
  
 
From the Anatomical Laboratory, Johns Hopkins University.
 
From the Anatomical Laboratory, Johns Hopkins University.
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==THE DEVELOPMENT OF THE BILE-CAPILLARIES AS REVEALED BY GOLGI'S METHOD==
 
 
By William F. Hendrickson. {From the Anatomical Laboratory of the Johns Hopkina University.)
 
 
 
 
As the diverticula of epithelial cells grow from the mid-gut and surround the omphalo-mesenteric veins to form the liver there is from the first a duct present, the primitive bile-duct. In the further growth of the liver these diverticula anastomose again and again to form the main bulk of the liver of the embryo. To what extent bile-capillaries are present in these masses may in part be determined by treating the livers of small embryos with Golgi's method, and at the suggestion of Dr. Mall 1 have made numerous tests with this method to determine its value in the study of the development of the bilecapillaries.
 
 
The lobule is formed rather late in the development of the liver. In the younger livers the portal and hepatic veins have each for themselves their own regions of tissue about them, which in no way interlace. A later shifting and new formation of vessels is required before we have any indication of a lobule. Human embryos of the fourth week have already formed the main bile-ducts and hepatic artery along the branches of the portal vein, but I have been unable to demonstrate any bilecapillaries in human or in pig's livers from embryos less than 5 cm. long.
 
 
Although it is probable that the bile-capillaries are formed directly from the lumina of the liver sprouts from the mid-gut, yet it is impossible to prove this by means of Golgi preparations. The pictures obtained by this method are just the reverse of those expected when the question is considered from the standpoint of embryology. The first bile-capillaries stained by Golgi's method are found immediately about large portal branches in embryos 5 cm. long. From this stage on the pictures show a gradual spreading in both peripheral and central direction until bile-ducts are reached on the one hand and the intralobular plexus on tlie other. It may be that the Golgi method stains only those bile-capillaries which contain secretion.
 
 
My successful specimens were obtained from human as well as pig's embryos 5 cm. long, and longer. A great many specimens were made from pig's livers, repeated tests having been made to stain the capillaries in the livers of young embryos. The great quantity of these embryos at my disposal allowed me to make many Golgi specimens of livers in which the artery, the portal vein, or both had first been injected in order to determine the vessel about which the first capillaries appeared. In addition to this I made serial sections usually about 50 /j. thick.
 
 
The first Golgi pictures are obtainable in the livers of pigs 5 cm. long (Fig. 1). Human embryos of the same size show a much more advanced network of bile-capillaries (Fig. 4). Yet repeated tests upon livers from pigs 5 cm. long always gave only a few capillaries in the immediate neighborhood of a large vein, which proved to be a branch of the portal vein. Specimens made by injecting either the portal vein or hepatic artery with a small quantity of Prussian blue before staining by Golgi's method always gave the same result, ('. e. that the bile
 
 
 
capillaries are first stained in the immediate neighborhood of the branches of the portal vein.
 
 
Fig. 2 is from a pig's embryo 6 cm. long. It shows the bile-capillaries somewhat more extensive, they having encircled the portal branch. In an embryo a little larger. Fig. 3, the capillaries have grown still more, for those encircling different portal branches nearly meet. In addition to this extensive spreading each main bile-capillary has upon it many small side twigs. It appears as if the first meshes enclosed bile-capillaries are cut up by these side branches shooting across from one capillary to the other as the meshes enlarge by the multiplication of liver cells. Only in some way like this could the proper number of bile-capillaries keep pace with the growth of the liver.
 
 
The process described in livers of pig embryos up to 8 cm. long must have all preceded the condition found in the liver of a human embryo 5 cm. long, for in the pig's liver and the human liver in these two respective stages the degree of development of the bile-capillaries is much alike. A glance at Figs. 3 and 4 will readily show this. The network of the human liver, however, is much larger than that of the pig, but this seems to be the case throughout development.
 
 
Fig. 5 represents the extent of the bile-capillaries in a pig's embryo 15 cm. long. We find here that the bile-capillaries growing about one of the branches of the portal vein have become continuous with those about like branches in the neighborhood. The only indication left of the manner of growth of the bile-capillaries is seen in the relative size of their meshes. The meshes next to the veins are smaller than those situated farthest from the vessel about which the bile-capillaries arose. This figure illustrates again the progressive subdivision of the meshes formed by the bile-capillaries. The meshes near the veins are more dense than those farther distant, and this is easily understood since we know that those around the veins appeared first.
 
 
In the human embryo 10 cm. long the bile-capillaries are again as far advanced as those in pig's embryos 15 cm. long. Their relative size and extent are shown in Fig. 6, which may be compared with Fig. 4, taken from a human embryo 5 cm. long.
 
 
Fig. 7 is from a pig's embryo 21 cm. long, and Fig. 9 from a human foetus at term. Both of these specimens show the network of capillaries distributed quite uniformly throughout sections, and at first thought it appears as if the growth of the capillaries was complete. But in the adult, both pig and human, the livers are considerably larger and the network is still smaller (Fig. 8).
 
 
If we had in the embryo's liver all the ludiments of the lobules of the adult liver it would not be so difficult to interpret these various pictures described above. In the livers of young embryos the portal and hepatic veins are in opposite ends of the liver, the portal being on the distal side and the hepatic on the proximal. When the liver is in this stage the
 
 
 
 
 
c
 
 
 
 
Fig. 1. — Piir, S cm. Ioue:.
 
 
 
 
 
 
 
Fig. '2, — Pijr, O cm.
 
 
 
 
 
 
 
 
c V"
 
 
 
 
 
 
Fig. 6. — ITuman, V) cm
 
 
 
 
Fig. T.— IMjf, 21
 
 
 
 
 
Fig. s.—Ailiilt pii;
 
 
 
 
 
 
Fig. il.— Human futiis at term.
 
 
 
 
 
Fig. 13.— Piur, li) cm
 
 
 
 
 
Fig. 10.— Piu-, .s cm.
 
 
 
 
 
Fiii. 14.— Piir, Hi cm.
 
 
 
 
 
Fig. ll.-Piij, Ki
 
 
 
 
 
Fiii. l.i.- Pis, -'!) .
 
 
 
 
Till; Jouss Hopkins Hospital Billetin Nos. 90-91.
 
 
 
 
September-October, 1898.]
 
 
 
 
JOHNS HOPKINS HOSPITAL BULLETIN.
 
 
 
 
221
 
 
 
 
bile-capillaries are first stained about the branches of the portal vein, although these veins cannot be called interlobular at this time. In the further growth of the vessels the hepatic veins invade the region occupied by the portal and vice versa. This process goes on, by what method we know not, until the lobules are finally formed. It is evident then that in the growth of the liver, as in bone, we must have destruction going on hand in hand with growth. Not only is this true during embryonic life, but Dr. Mall also informs me that a similar process is taking place in the lobule after it is formed. In this latter instance tiie liver lobule is constantly undergoing destruction in its centre and being regenerated at its periphery.
 
 
These facts complicate our problem considerably and make it practically impossible for us to interpret our specimens correctly. It appears, however, that in the further development of the liver the bile-ducts grow longer and longer at the expense of the bile-capillaries. At best the Golgi specimens indicate this, and, therefore, I can describe this process.
 
 
In the liver of a pig's embryo 8cm. long, the bile-capillaries
 
 
 
 
immediately about the portal vein are somewhat more marked than those more distant. This is shown in transverse section in Fig. 10, and in longitudinal section in Fig. 11. This process is still more advanced in embryos 16 cm. long (Fig. 12), and in a measure we can speak of this large black capillary as a bileduct. At first the dilatation is even and regular (Fig. 11), but soon it becomes irregular, the meshes become smaller and smaller until a member of capillaries together form a distinct bile-duct. The successive stages of this process are shown in Figs. 13, 14 and 15, and the completed duct is shown in.Fig. 8. When the duct is completed the bile-capillaries communicate in great part only with its tip, and not all along its course as in the case of the younger ducts. This question, however, needs further investigation in normal as well as in diseased livers.
 
 
PLATE.
 
 
In all the figures the outlined and striated space is a branch of the portal vein. All the figures were drawn with the camera and are enlarged 53 times.
 
 
 
 
A STUDY OF THE MUSCULATURE OF THE ENTIRE EXTRA-HEPATIC BILIARY SYSTEM, INCLUDING THAT OF THE DUODENAL PORTION OF THE COMMON BILE-DUCT AND OF THE SPHINCTER.
 
 
By William F. Hendrickson.
 
 
 
 
(Prom the Anatomical Laboratory of the Johns Hopkins University .)
 
 
 
 
The idea that there is a sphincter muscle about the orifice of the ductus communis choledochus has been held since the time of Glisson. In the year 1887, however, Ruggero Oddi, an Italian, had cause to inquire more particularly into the subject. He found that no extended research had been made in this connection, and that the idea of a sphincter muscle of the common bile-duct was based for the most part on conjecture. Oddi accordingly undertook a careful study of the subject and used two methods : (1) maceration, (2) sectioning and microscopic examination.
 
 
With the maceration method he examined and described the sphincter muscle of the dog, which he regards as typical, and this description is followed by some observations regarding the differences observable in the sphincter muscle of the sheep, ox and hog. Oddi does not attempt to demonstrate the sphincter muscle in man by this method.
 
 
He studied also serial cross-sections of the duodenal portion of the common bile-duct of the dog and other animals, and describes them briefly.
 
 
The importance of such studies for the clinician interested in diseases of the biliary passages is obvious, and it is to be regretted that Oddi's material did not permit him to extend his studies to the bile-ducts of man. He states, it is true, that he has studied sections of the human bile-duct, and that he found sphincter fibres around the end of the bile-duct; otherwise his research deals entirely with tissues derived from animals.
 
 
In view of this fact a reworking of the subject with par
 
 
 
ticular reference to human beings has seemed desirable, and the present work was therefore, at the suggestion of Dr. Lewellys F. Barker, undertaken. This report includes, it is believed, as full an account of the musculature of the biliary passages of man as the methods employed will permit of, and also contains references to a number of points hitherto unstudied in the structuie of the biliary passages of animals.
 
 
I. — History.
 
 
II. — Methods employed.
 
 
(a) Maceration with a mixture of nitric acid, glycerine and water.
 
 
(b) Maceration with Ranvier's alcohol.
 
 
(c) Stained celloidin and paraffin sections.
 
 
III. — The Musculature of the Biliary Passages in the Dog.
 
 
(a) Gall-bladder.
 
 
(b) Cystic duct.
 
 
(c) Hepatic duct.
 
 
(d) Common bile-duct.
 
 
(e) Place of union of cystic, hepatic and common bileducts.
 
 
(f) Duodenal portion of common bile-duct.
 
 
IV. — The Musculature of the Biliary Passages in the Rabbit.
 
 
(a) Gall bladder.
 
 
(b) Cystic duct.
 
 
(c) Hepatic duct.
 
 
(d) Common bile-duct.
 
 
 
 
222
 
 
 
 
JOHNS HOPKINS HOSPITAL BULLETIN.
 
 
 
 
[Nos. 90-91.
 
 
 
 
(e) Place of union of cystic, hepatic and common bileducts.
 
 
(f) Duodenal portion of common bile-duct.
 
 
V. — The Musculature of the Biliary Passages in Man.
 
 
(a) Gall-bladder.
 
 
(b) Cystic duct.
 
 
(c) Hepatic duct.
 
 
(d) Common bile-duct.
 
 
(e) Place of union of cystic, hepatic and common bileducts.
 
 
(f) Duodenal portion of common bile-duct.
 
 
VI. — Conchisions.
 
 
VII. — Index Lettering of the Figures.
 
 
I.— HISTORY.
 
 
For convenience the literature will be divided into two groups.
 
 
(a) That concerning the smooth muscle of the gall-bladder, cystic, hepatic and common bile-ducts.
 
 
(J) That on the structure of the duodenal portion of the common bile-duct.
 
 
ad (rt) In 1761 Duverney* described the gall-bladder of man and divided its wall into four coats, the second coat being the muscular. The fibres which composed it were diversely arranged, some being longitudinal, others transverse or oblique. The fibres near the neck of the gall-bladder showed a circular disposition, and might be regarded as a sphincter.
 
 
In 1829, Wilsonf declared that the presence of muscle fibres in the gall-bladder and the gross bile passages had not been demonstrated.
 
 
Koel)iker| considered the nrasculature of the large bile-ducts to be but very little developed in man. He could not find a trace of muscle in the hepatic duct or in its branches. Bundles of suiooth mu!j( ie were foiind, however, in the ductus choledochus and in the ductus cysticus, but not in suflBcient quantity to justify the description of a muscular coat.
 
 
Only in the gall-bladder was a true muscle coat to be seen; here the muscle bundles crossed in all directions; still those running longitudinally and transversely predominated.
 
 
Tobien§ stated that muscle fibres are present in the human gall-bladder and that they run in all directions. The cystic duct, similar to the hepatic duct of man, contains no muscle. The presence of a ring of muscle fibres in the cystic duct near the gall-bladder was, however, confirmed by him. This ring of
 
 
 
 
♦Duverney (J.-G.) Oeuvrea anatomiques. I'rvris, 1761, t. ii, p. 234.
 
 
f Wilson (C.) Observations on the mechanism of the biliary system. Edinb. M. & S. J., 1829, xxxi, 107-114.
 
 
tKoelliker (A). Ztsch. f. wissensch. Zool. Leipz., 1848, S. 61-62.
 
 
J Tobien (A. I,) De glandularum ductibus effercntibus, ratione imprimis habita telse muscularis. Dissertatio Inauguralis, borpat, 1853, S. 17.
 
 
 
 
muscle is made up of contiguous muscle fibres, no connective tissue penetrating between them. He cites Glisson* and Duverney as supporters of the view that a sphincter of the gall-bladder exists, and names G. H. Meyerf as being of the opposite opinion.
 
 
EberthJ found in man and in the cat and dog, smooth muscle in the gall-bladder only. In each case the muscle fibres run for the most part in a circular direction ; longitudinal and diagonal bundles are, however, present.
 
 
Luton§ describes the middle coat of the biliary passages as consisting of fibrous connective tissue, in which are some muscle fibres. In general the muscle fibres are not abundant, especially in the hepatic duct, cystic duct and common bileduct. In the gall-bladder he finds a thin muscular coat, the fibres of which take two courses, viz. longitudinal and transverse.
 
 
MacAlisterJI believes that muscle fibres are present in what he calls the fibro muscular coat of the human gall-bladder. The muscle fibres run both circularly and longitudinally, but those of the latter direction constitute only about one-fourth of the whole number. In his description of the valvular folds of the cystic duct, he states that some muscle fibres are present in the bases of the upper valvular folds, but they do not seem to exist in the lower folds, i. e. those nearest the common bileduct.
 
 
Paulet^ found in the connective tissue of the biliary passages some contractile cells. The nirmber present was not sufficient to form a continuous coat. Moreover, according to his statement the muscle fibres become less numerous as the calibre of the tube becomes larger. They are scanty in the cystic, hepatic and common bile- ducts of man. The gall-bladder also contains a certain number of smooth muscle cells, but never sufficient, at least in normal cases, to form a distinct coat.
 
 
According to Variot** the human gall-bladder contains a network of smooth muscle fibres, the interstices being filled with connective tissue. The common bile-duct exhibited in one case (human adult) discontinuous longitudinal muscular fasciculi; in another case (human adult) only a few circular bundles. In the dog, two superimposed strata of smooth muscle fibres were found which, very thick near the ampulla of Vater, became gradually thinner as the gall-bladder was approached. Between these strata of muscle is interposed a nervous apparatus analogous to that of the intestine.
 
 
 
 
Glisson (Francis.) Anatomia hepatis ; cui praemittuntur quaedam ad rem anatomicam universe spectantia. Et ad calcem operis subjiciuntur nonnulla de lymphse ductibus nuper repertis. 16°. Hagae, A. Leers, 1681.
 
 
f Meyer (G. H.) De musculis in ductibus eflerentibus glandularum. Berl., 1837, p. 31.
 
 
t Eberth (C. J.) Ztsch. f. wissensch. Zool., Bd. xii, 360, 1862.
 
 
§ Luton (A.) Biliaires (voies). N. diet, de med. et chir. prat., Par., 1866, v, 33-101.
 
 
II Mac.\lister (A.) Contributions to the comparative anatomy and physiology of the gall-bladder. Med. Press and Circ, Dubl., 1867, n. s. iv, 129 and 150.
 
 
1JPaulet(V.) Biliaires (voies). Dictionnaire encyclop^dique des sciences medicales. Paris, 1868, vol. ix, p. 295 ; 31-1.
 
 
Variot (G.) Sur les nerfs des voies biliaires extra-h^patiques. Jour, de I'anat. et physiol., etc., Par., 1882, xviii, 600-610.
 
 
 
 
September-October, 1898.]
 
 
 
 
JOHNS HOPKINS HOSPITAL BULLETIN.
 
 
 
 
223
 
 
 
 
Sappey* in describing the structure of the human gallbladder states that with the connective tissue composing the tunica conjunctivale and which forms a loose feltwork structure, are mixed some very delicate elastic fibres and some thin fasciculi of smooth muscle, scanty in man but more abundant in some mammals. The human cystic duct contains a plexiform arrangement of smooth muscle fibres. The ductus communis choledochus exhibits a structure identical with that of the other bile-ducts. In the hepatic ducts the diameter of virhich is 0.5 mm. or more he sees smooth muscle fibres which extend throughout the whole extent of the biliary passages. These fasciculi even in the large branches are very delicate and much separated. They exhibit a plexiform arrangement.
 
 
Cruveilhier"! was not able to see the muscle fibres which other authors describe in the human gall-bladder, and ignored the possibility of the presence of muscle in the human cystic, hepatic and common bile-ducts.
 
 
Henle| believes the human gall-bladder contains smooth muscle fibres which interlace with one another. He finds no muscle in the human cystic, hepatic, and common bile-duets, and considers the accumulation of ring-shaped muscle fibres described by Tobien as a sphincter vesicffi fellae, to belong not so much to the cystic duct as to the neck- of the gall-bladder. Henle experimented upon a beheaded man to determine the contractility of the biliary passages but with negative results.
 
 
Testut§ finds in the human gall-bladder smooth muscle fibres interlacing in all directions and bound together by connective tissue. In the cystic duct, only longitudinal muscle bundles are seen. The common bile-duct contains in its walls smooth muscle, well developed near the ampulhi of Vater but on ascending the duct; this becofnes less and less prominent until the muscle is even entirely absent at certain points in the duct.
 
 
Gegenbaur|| states that in the connective tissue of all the human bile passages (cystic, hepatic and common bile-ducts) smooth muscle cells are to be found. In the wall of the gallbladder they form a very thin coat, network like in character. Sometimes an indistinct longitudinal and circular coat can be made out.
 
 
Schiifer and SymingtonTJ state that the human gall-bladder contains plain muscle fibres which assume for the most part a longitudinal direction but some run transversely. They believe that the cystic and hepatic ducts also contain longitudinal and circular muscle fibres.
 
 
ad {b) — The presence of a sphincter muscle about the duodenal extremity of the common bile-duct was suspected as early as 1681. In that year Glisson** gave the following description :
 
 
 
 
• Sappey (M. P. C.) Traite d'anatomie descriptive. Paris, 1889, t. ill, p 273.
 
 
tCruveilhier (J.) Traite d'anatomie descriptive. 5 ed., 8°, Par., 1867-74.
 
 
t Henle (F. G. J.) Handbuch der aystematischen Anatomie des Menschen. 8°. Braunschweig, 1856-73.
 
 
§Te8tut(L.) Traite d'anatomie humaine, etc. Paris, 1889-91.
 
 
II Gegenbaur (C. ) Lehrbuch der Anatomie des Menschen. 5. Aufl. 8°. Leipzig, 1892.
 
 
K Qualn's Anatomy. 10. ed. London and New York, 1892.
 
 
0p. cit.
 
 
 
"Quamprimum autem ductus hie communis utranque exteriorem intestini tunicam perrupit, adeo laxe eum interior tunica complectitur, ut digito hue illuc facillime dimoveri queat: hujusque mobilitatis ratione rem quamlibet ab intestine illapsuramarcet: quemadmodum id exploratu facile est, si mode, aperto intestino, acum aut specillum exiguum iliac immittere coneris. Videbis enim, vario hue illuc subterfugio, spem omnem penetratiouis eludere; nisi forte statim ipsum centrum illius, stylo tetigeris.
 
 
Prseterea, ne quid ab intestine in ductum hunc illabatur, ipsa insertionis obliquitas in causa est : quic quid enim illo vorsum tendit, atque ingredi eonatur, id simul eodem nisu interiores intestini tunicas versus exteriorem comprimit, ipsumque adeo aditum pra3cludit: idque eo magis, quo vis illata potentior fuerit.
 
 
Denique, regressus omnis in ductum communem prsepeditur a flbris anularibus, qua3 non modo orificium ipsum, sed & totum obliquum tractum obsident. Quemadmodum enim fibrae istse anulares sese facile extendunt, queties humor biliosus diutule repressus eepiaque jam adauctus ad exitum properat; ita quoque, elapse semel superfine humore illo, esedem penitus connivent, transitumque omnem impediunt, donee humoris plusculum denue cellectum fuerit, quod fores illarum effringat. Dari autem ejusmodi fibras anulares hinc constat: Si intestinum ex adverse orificii hujus aperueris, bilenique in illud digitorum opera adegeris, videbis statim ab exclusa bile orificium illud sponte sua denuo occludi; quod sane cirra ejusmodi fibrarum epem, fieri nequaquam posset. Similiter, si insertioni huie specillum indideris, idemque mex inde extraxeris; orificium jam dictum spontanes motu contrahi cernes. Ideoque crediderim aditum hunc eo nomine cum anisphinctere convenire, licet miuore cum molimine clausura illic peragatur: nempe, si quande ab incumbente humore copioso molestia aliqua illata fuerit, mediantibus fibris hisce anularibus transitum ei concedit, denuoque in angustiam pristinam sese centrahit.
 
 
Ductus communis in eve aliter, quam in homine in intestinum inferitur. Quippe in ilia, unicas integrse spatio inter intestini tunicas prorepit, priusquam in illius cavum aperitur; tumque fissuram efformat, qiise per intestini longitudinem deducitur. Fissura haec laxa & spongiosa protuberantia, ab interiore intestini tunica enata, utrinque pretegitur: adeo ut, si quidpiam altrinsecus in illam impingat, id earn protinus translabatur, hiatumque occludat. Ipsa tamen insertionis hujus obliquas in ovibus longitude, prsecipue impediniento est, quo minus aliquid ab intestinis in ductum hunc communem regrediatur; quoniam enim orificium ejus in eblongam fissuram desinit, fibris ejusmodi anularibus nihil opus erat. Neque etiam insertie haec in ovibus sque laxe hue illuc eberrat, atque in homine id fieri diximus: ac propterea, quoniam aliis jam dictis auxiliis destituitur, sequum erat, ut itineris longitudo, tunicarumque an iuvicem areta cempressio, illorum absentiam compensarent."
 
 
In 1869, Von Luschka* examined the intestinal portion of the common bile-duet of man and found a longitudinal open
 
 
 
 
Von Luschka (H.) Die Pars intestinalia des gemeinsamen Gallenganges. Vrtljschr. f. d. prakt. Heilk., Prag., 1869, ciii, 86-100.
 
 
 
224
 
 
 
 
JOHNS HOPKINS HOSPITAL BULLETIN.
 
 
 
 
[Nos. 90-91.
 
 
 
 
ing in the outer longitudinal coat, and a transverse opening in tlie inner circular muscular coat of the intestine which gave passage to the duodenal portion of the common bile-duct.
 
 
In 1887, R. Oddi* undertook to demonstrate the sphincter of the common bile-duct. He says: "I have found that no one has made a research upon this svibject, although some, either by imagination or conjecture, have assumed the existence of such an arrangement."
 
 
Oddi employed in his investigation the macerating fluid proposed by Marcacci — a mixture of equal parts, by volume, of concentrated nitric acid, glycerine and water. The duodenal portion of the common bile-duct (of the dog, sheep, ox and hog) was examined with the best results. Oddi did not examine human specimens with this method. He mentions the following points as the result of a study of macerated specimens from animals belonging to different species. The course of the common bile-duct which runs across the intestinal tunic varies with the animal. Around the last part of the common bile-duct, almost in proximity with the mouth of the duct, he sees a muscular ring ; this ring, after the removal of some delicate loops which run from its external surface to become lost in the muscle of the intestine, can be considered as independent.
 
 
Little by little, as the point of entrance of the common bileduct into the intestinal wall is approached, the fusion of the circular fibres of the common bile-duct with the intestinal wall becomes more intimate, so that the common bile-duct cannot any longer be elevated. This may be due to the fact that of the circular fibres of the common bile-duct some run off to become implanted on the circular muscle of the intestine ; like cords, fastened at the two poles of an oval, they go to become fixed at two firm points opposite one another in order to attain support. After these bonds have been cut the common bile-duct with its circular fibres can be isolated for some distance, up to the point where it plunges through the circular muscular fibres of the duodenum. Here the bile-duct raises the circular muscle fibres of the duodenum, forming a wedge-shaped opening. Oddi says it must be noted that in the animals examined by him, these fibres (sphincter fibres) did not appear always equally disposed, but necessarily assumed that form and disposition which could best adapt itself to the form and course of the common bile-duct in the intestine. Thus, in the sheep and the ox, where the common bile-duct runs parallel to the intestinal axis, they are hidden and parallel to the intestinal fibres; in the dog, in which case the common bile-duct runs obliquely to the axis of the intestine, they are oblique and less hidden ; while in the hog, where the common bile duct has a course like a " C ", they are so strangely disposed as to be difficult to describe.
 
 
Oddi studied microscopically, sections cut transverse or perpendicular to the axis of the intestine of various animals at different levels. The following descriptions of the dog and sheep are given as typical. In a section taken at the point where the common bile-duct has just entered the muscular wall of the intestine, there is seen externally the stratum
 
 
 
 
Oddi, R. Di una specials disposizione a sfintere alio sbocco del coledoco. Ann. d. Univ. libera di Perugia. Fac. di med. e chir., 1886-7, ii, 249-264, 1 pi. Also, Reprint, Perugia, 1887.
 
 
 
 
longitudinale of the muscular coat of the intestine, and just internal to this the stratum circuiare which presents a buttonhole-like arrangement of its fibres through which the common bile-duct is seen to pass ; the bile-duct is thus embraced by two muscular coats (formed by the buttonhole-like arrangement of the fibres of the stratum circuiare), which reunite at its poles. Between the poles of the common bile-duct and the angle of reunion of the two muscular layers, there remains a triangular space, the base of which is formed by circular muscle fibres which both on the exterior and on the interior are inextricably mixed with the two circular muscular layers above mentioned. At the side of the circular muscle fibres just described are seen longitudinal fibres quite noticeable in section.
 
 
If the section be taken a little nearer the middle of the course of the common bile-duct, it is seen that the internal muscular layer has become thinner, while the external has acquired greater volume. Between the two layers the section of the duct can be seen, surrounded by a true muscular ring which is not intimately related with the two intestinal muscular layers. The muscular ring of the duct seems, in the section, to be entirely independent.
 
 
A section near the mouth of the common bile-duct shows that the division of the circular muscular layer of the intestine no longer exists — the ring described remains only in slight contact with the inner surface of the fibres of the stratum circuiare of the intestinal muscular tunic. A continuation of the longitudinal fasciculi at the poles of the common bileduct is also seen.
 
 
Oddi next proceeds to give some points distinguishing the animals examined from one another. • A characteristic disposition of the muscle is, he says, proven for the rabbit. The muscular ring which envelops the common bile-duct appears in a section transverse or perpendicular to the long axis of the intestine. He emphasizes this fact, for it demonstrates, he thinks, the independence of these fibres from those of the intestine. In man, owing to the fineness of the muscle fibres, the disposition is not characteristic. Nevertheless, the circular as well as the longitudinal fibres (at the poles of the lumen of the common bile-duct) are very manifest. The circular fibres, however, cannot be followed for a great distance around, since, for the more part, they become lost in the connective tissue which supports the mucous membrane in its numerous anfractuosities. The fibres here mentioned have but little relation to the muscular layers of the intestine.
 
 
As to a special disposition of the muscular fibres at the mouth of the pancreatic duct, Oddi states that in the duodenum of a dog prepared by Marcacci's method of maceration, he was able to see at the mouth of the pancreatic duct (which is obliquely distant about two inches from the mouth of the common bile-duct) some special fibres disposed in a ring, very delicate and quite distinct from the intestinal muscular coats. This arrangement was confirmed by transverse and longitudinal sections taken at the mouth of the pancreatic duct.
 
 
II.— METHODS EMPLOYED. In the present investigation three methods were employed to demonstrate the smooth muscle of the biliary passages.
 
 
 
 
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(a) The most important of these, in some respects, is the method used by Marcacci* for demonstrating the muscuhiture of the papilla mammffi. The method consists in macerating the tissue to be examined in a niistiire of equal parts by volume of concentrated nitric acid, glycerine and water.
 
 
In applying it to the present study, the vertical portion of the duodenum was cut out and ligated at its two extremities. A cannula was introduced into the ductus choledochus and the above-mentioned mixture was injected into the intestine until its walls were well distended. The common bile-duct was next ligated and the entire specimen placed in a vessel full of the same macerating mixture. After a certain period of time the tissue was removed and placed in water. The intestine having been cut open on the side opposite the mouth of the common bile-duct, the mucous membrane was removed quite easily with forceps. The water was changed and the specimen allowed to remain thus for 24 hours. At the end of this time the specimen is ready for examination. The muscle fibres have the color and brilliancy of raw silk and, having absorbed water, stand out quite beautifully.
 
 
To demonstrate the muscle of the gall-bladder, cystic duct, hepatic duct and common bile-duct, the gall-bladder and hepatic duct were dissected from the liver; the hepatic duct was ligated and after ejecting the bile through the common bile-duct by pressure on the gall-bladder, the macerating mixture was injected up the common bile-duct until the walls of the gall-bladder were distended. The common bile-duct was then ligated and the whole mass placed in a vessel containing the same macerating mixture. The rest of the process is the same as for the duodenal specimen.
 
 
The period of maceration in nitric acid, glycerine and water has to be varied according to the delicacy of the specimen.
 
 
(b) Another method employed with advantage was that of maceration in Ranvier's alcohol. This method was found most useful in making permanent preparations of the gall-bladder. The gall-bladder, having been cut open, was allowed to macerate in Ranvier's alcohol for a week or ten days. The specimen was then removed and the epithelial cells brushed away with a stiff camel's hair brush. The serous coat and outer connective tissue coat were removed with forceps. The specimen was then stained with alum carmine or with hematoxylin and eosin and mounted in Canada balsam with the mucosal side down. This gives a bird's-eye view of the arrangement of the muscle in the wall of the gall-bladder.
 
 
(c) The third method employed was that of fixing, embedding, sectioning and staining the various parts. The specimens were fixed in absolute alcohol, formalin, or corrosive sublimate and imbedded in celloidin or paraffin. The principal stain used was that suggested by Van Gieson since the differentiation of minute quantities of smooth muscle from the surrounding connective tissue by this stain is quite exquisite. Other methods of staining were, however, employed for purposes of comparison.
 
 
 
 
Marcacci (A). II muscolo areolo-capezzolare. Gior. di R. Accad. di med. di Torino. 1883, 3. S., xxxi, 743-753. Also.TransI.: Arch. ital. de bid., Turin, 1883. iv, 292-254.
 
 
 
 
III.— THE MUSCULATURE OF THE BILIARY PASSAGES IN THE DOG.
 
 
(a) Gall-bladder. — Specimens macerated in a mixture of nitric acid, glycerine and water showed the arrangement of smooth muscle to be plexiform. The circular or transverse fibres are most numerous. The gall-bladders macerated in Ranvier's alcohol showed an arrangement exactly like the above. Longitudinal celloidin sections cut from the body of the gall-bladder, showed smooth muscle running in three directions, transverse, longitudinal and diagonal. Fig. 1.
 
 
Most of the muscle bundles run around the gall-bladder in a transverse direction, i. e. in a direction perpendicular to the long axis of the gall-bladder. The muscle bundles are not arranged in definite and regular coats; the transverse, longitudinal and diagonal bundles mingle without conformity to any rule. The muscle bundles are more or less separated from one another by a certain amount of connective tissue, but since the individual muscle bundles overlap, there are few if any places in this coat where muscle is entirely absent.
 
 
(J) Ci/slic duct. — Macerations in a mixture of nitric acid, glycerine and water revealed the presence of both transverse and longitudinal muscle fibres. In celloidin sections cut parallel to the long axis of the tube smooth muscle can be demonstrated running in three directions, transverse, longitudinal and diagonal. Fig. 2.
 
 
The absolute amount of transverse and longitudinal muscle is about equal. The diagonal muscle fibres are many fewer in number. The general arrangement of the smooth muscle bundles is plexiform. The connective tissue penetrates between the muscle bundles to a degree relatively greater than in the gall-bladder. Fig. 3 is taken from one of the valves of Heister. It is the largest fold found in tliis specimen and presents an arrangement of muscle which is much more accentuated in human specimens {vide infra). No such ai-rangement was found in the cystic duct of the rabbit.
 
 
In the cystic duct of the dog portions of the longitudinal muscle bundles curving around and running out into the valve can be made out. Other bundles of muscle, having origin apparently in the circular or transverse fibres of the cystic duct, run out into the valve. The report of the study of the Ileisterian valves of human beings is accompanied by a detailed account of this arrangement.
 
 
(c) Hepatic duct. — Longitudinal muscle fibres were found in specimens macerated in a mixture of nitric acid, glycerine and water. Longitudinal sections of the hepatic duct showed only longitudinal fibres. Fig. 4. The fibres are but few in number and the disposition of the muscle is such that there can be no talk of a continuous coat.
 
 
(d) Common bile-duct. — Macerations in a mixture of nitric acid, glycerine and water showed a few longitudinal muscle fibres. Longitudinal celloidin sections showed smooth muscle running in three directions, longitudinal, transverse and diagonal. Fig. 5. The longitudinal bundles are most numerous, the transverse bundles next in number, the diagonal bundles being least numerous. The muscle fibres do not form a complete coat; they are found scattered amongst much connective tissue.
 
 
(e) At the place of union of the cystic, hepatic and common
 
 
 
 
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bile-ducts, no extraordinary muscular arrangement was seen. Each duct preserved its normal structure, the wall of each gradually merging into that of the others.
 
 
(/) Duodenal por/io7i of the common bile-duct. — That portion of the duodenum which contains the duodenal papilla having been macerated in a mixture of nitric acid, glycerine and water as described above, was exariiined in the following manner: The intestine was cut along its longitudinal axis on the side opposite the duodenal papilla and laid open. The mucous membrane was removed and with it the muscularis mucosa. The appearances at this stage are represented in Fig. 6.
 
 
From the point where the common bile-duct enters the intestine A to the point B, the muscle fibres of the inner circular muscular coat of the intestine are seen to pass over the common bile-duct. From the point R, to the point O, an irregular arrangement of muscle bundles is seen to exist. This arrangement resembles in shape more or less that of a mark of interrogation placed in a horizontal position. The structure has its origin (1) partly in the fibres of the inner circular muscular coat of the intestine, (2) partly in fibres which lie under the inner circular muscular coat and which arise from the median line of the bile-duct and (3) partly from the ring of muscle surrounding the mouth of the bile-duct. The fibres after this origin run forward (i. e. towards the lower end of the duodenum) and, passing under the fibres of the inner circular muscular coat of the intestine, blend with the fibres of the outer longitudinal muscular coat.
 
 
Out of eight specimens I found no two cases in which this irregular arrangement was alike. A description of the mode of origin and termination of these muscle bundles is accordingly of but little value, although an exact determination was made in each case.
 
 
Continuing from the point to the mouth of the common bile-duct J/, one can see muscle fibres running around the end of the common bile-duct. A careful examination of this region shows that a complete ring of muscle surrounds the mouth of the common bile-duct. At the same time, close observation reveals a certain number of muscle fibres running ofl' from the two sides of this annulus of muscle. These latter are in reality part of the ring of muscle and after separating from the ring at its sides bend abruptly forward, i. e. towards the lower end of the duodenum. This ring of muscle with the lateral muscle bundles arising from it constitutes the sphincter of the ductus communis choledochus.
 
 
In Fig. 6 the muscle bundle seen coming off from the nonpancreatic* side (see X) of the annulus of muscle corresponds with the arrangement usually found. At first sight there seems to be no corresponding bundle for the other side (i. e. pancreatic side) of the muscle ring. It will be remembered, however, that the structure similar to a mark of interrogation had its origin in part in some fibres of the muscle ring about the mouth of the common bile-duct. These fibres of origin, in this case, take the place of the muscle bundle which runs off
 
 
 
 
The terms non-pancreatic and pancreatic are used here to discriminate between the two sides of the bile-duct. The pancreatic side is so called because the common bile-duct is usually joined on this side by the duct of Wirsung.
 
 
 
 
at the pancreatic side of the muscle ring. The fasciculus on the pancreatic side of the muscle ring must terminate, after running forward a short distance, as described above in connection with the termination of the structure resembling a mark of interrogation — by passing under the fibres of the inner circular muscular coat of the intestine and blending with the fibres of the outer longitudinal coat. The fasciculus on the non-pancreatic side of the muscle ring, after running forward a short distance, curves slightly to the pancreatic side and finally terminates by mixing superficially with the fibres of the inner circular muscular coat of the intestine. The manner of termination of these lateral fasciculi of the annulus about the mouth of the common bile-duct varies somewhat. They end:
 
 
(a) By mixing superficially with the fibres of the inner circular muscular coat.
 
 
(b) By passing more or less abruptly under the fibres of the inner circular muscular coat and becoming lost among the fibres of the outer longitudinal coat.
 
 
(c) One lateral fasciculus may resemble description given under (a) ; the other may resemble that given under (b). An illustration of this is given in Fig. 6.
 
 
After this preliminary study an incision was next made along the median line of the common bile-duct extending from the point A to the point R. The fibres of the inner circular muscular coat of the intestine were then peeled off the bile-duct on both sides of the incision. The structure shown in Fig. 7 was revealed. Along the median line of the common bile-duct, a number of muscle fasciculi can be seen to arise. From this origin the muscle bundles run down and forward (towards the lower end of duodenum) over both sides of the common bileduct. As the fibres on either side of the common bile-duct run forward they unite, forming a relatively large bundle of muscle on each side of the bile-duct and in direct contiict with it.
 
 
The manner of termination of these bundles of muscles (running parallel with the bile-duct) varies somewhat. They end :
 
 
(a) By running forward and around under the ampulla of Vater, becoming continuous with fibres of t)ie inner circular muscular coat of the intestine.
 
 
(b) By running forward, turning away from the bile-duct and blending with fibres of the inner circular muscular coat of the intestine.
 
 
(c) By running forward, passing under the annulus of muscle about the mouth of the common bile-duct and becoming lost among these fibres.
 
 
(d) One side ends according to (b) ; the other side according to (c).
 
 
The mode of termination in Fig. 7 corresponds to that described under (c).
 
 
At the point 0, Fig. 7, some fibres of the inner circular muscular coat bend around the common bile-duct forming a Ushaped curve. This is the place of entrance of the common bile-duct into the muscle of the inner circular muscular coat of the intestine.
 
 
The common bile-duct is finally teased completely away and the muscle fibres of the inner circular muscle coat are revealed. These muscle fibres are found to be present from the point A to the point M, Fig. 6. It will be remembered that fibres of
 
 
 
 
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the iuner circular muscular coat pass over the common bileduct from the point A to the point B. Removal of the remaining fibres of the inner circular muscular coat discovers the outer longitudinal muscle coat of the intestine. In Fig. 8, the point F represents the arrangement of the fibres of the outer longitudinal muscle coat of the intestine at the place of entrance of the common bile-duct into the intestinal wall.
 
 
In addition to this general description the following points deserve to be mentioned. In some specimens at the pancreatic side of the mouth of the common bile-duct additional muscle bundles more or less involved with some already described can be made out. The resulting structure suggests a point d'appui. One never sees such a point d'apjnii developed on the non-pancreatic side.
 
 
In all cases the course of the common bile-duct through the wall of the duodenum is slightly oblique with reference to the inner circular muscle coat of the intestine; in most cases the course is also slightly curved — the convex side being the pancreatic side of the common bile-duct.
 
 
The Duct of Wirsung. — Speaking relatively, the duct of WirBung was found in many cases to run among the muscle fibres of the point d^appui situated at the pancreatic side of the mouth of the common bile-duct. The duct of Wirsung joins the common bile-duct at its extreme end; the pancreatic and common bile-duct opening side by side. The annulus of muscle fibres aboi^t the mouth of the common bile-duct accordingly also embraces the mouth of the duct of Wirsung.
 
 
In Fig. 8, point W, the arrangement of the outer longitudinal muscle coat of the intestine at the point of entrance of the duct of Wirsung into the intestinal wall is illustrated.
 
 
A study of serial cross- sections of the duodenal portion of the dog's common bile-duct. — Two sets of serial sections were prepared and examined. The specimens were stained in bulk with borax carmine and embedded in paraffin. The following drawings are taken from sections at different points in the course of the common bile-duct through the intestinal wall. They begin near the duodenal papilla and pass back towards the point of entrance of the duct into the intestinal wall. (Figs. 9 to 13).
 
 
Fig. 9 is made from a cross-section taken through the duct of Wirsung and the common bile-duct near their junction. Most interest attaches to the appearances in the submucosa. Here are to be seen two oj)enings with irregular contours. The one to the right — the larger — is the lumen of the ductus communis choledochus. The other is the lumen of the duct of Wirsung. Surrounding these lumina, so as to embrace them, are bundles of smooth muscle. The figure shows one muscle bundle traversing the space between the two lumina and connected above and below with other muscle bundles in such manner as to form a double ring of muscle embracing the two ducts. The ring of muscle here shown corresponds to the muscle ring about the mouth of common bile-duct found in macerated specimens. Examination of second set of serial sections in this region showed the muscle ring embracing both the common bile-duct and the duct of Wirsung, but in this instance no distinct bundle of muscle could be seen traversing the space between the two lumina. Apparently no one has suspected, up to the present time, the existence of this double
 
 
 
 
muscle ring embracing the mouths of the common bile-duct and ihe duct of Wirsung.
 
 
On both sides of this double ring of muscle one can make out muscle bundles cut transversely. In two or three places the bundles of the muscle ring are connected with these transversely cut fibres. These bundles (transversely cut) as well as others seen below lying on the inner surface of the inner circular muscular coat of the intestine, represent sections of those lateral fasciculi which in macerated specimens are seen to have origin in the ring of muscle about the mouth of the common bile-duct and to bend around and run down in the duodenum (see X). Other sections show these lateral fasciculi terminating by mixing superficially with the muscle fibres of the inner circular mttscular coat. It is to be noted that the lumen of the common bile-duct is partially filled with folds of mucous membrane at this point.
 
 
Fig. 10 is taken at a point further away from the month of the common bile-duct. In this section only one lumen is present, that of the common bile duct. The lateral fasciculi which have origin in the ring of muscle about the mouth of the common bile-duct, and which bend around and run down the duodenum are, however, shown here quite well. The mass of muscle to which the lateral fasciculus runs (on the left) probably represents the jjoint d'appui noted in the macerated specimens.
 
 
Fig. 11 is taken at a point about midway in the course of the common bile-duct through the intestinal wall. The structures show the division of the inner circular muscular coat of the intestine. Part passes over and part passes under the common bile-duct. Where the two parts of the inner circular muscular coat unite on either side of the common bileduct to form the complete inner circular muscular coat again, muscle fibres can be seen running from the upper to the lower part. This occurs on both sides, and there is, therefore, a complete ring of muscle around the duct. This arrangement must not, however, be regarded as perfectly symmetrical. Furthermore, some sections in this region show a simple decussation of fibres of the upper division with fibres of the lower division of the inner circular muscular coat. This latter arrangement (decussation on both sides of the common bile-duct) seems to hold entirely for the second set of serial sections. On both sides of the lumen of the common bile-duct, muscle bundles in transverse section are seen. These represent those bundles of muscle which have origin in the median line of the common bile-duct and afterwards run forward parallel with the long axis of the tube (see N ).
 
 
Fig. 12 shows those muscle bundles which arise in the median line of the common bile-duct. They are seen here only on the right, running down over the side of the bile-duct (see iV) ; it should be noted, however, that this arrangement is bilateral. The bundles of muscle cut transversely represent those muscle bundles which run forward, parallel with the common bile-duct, after taking their origin in the median line of the bile-duct.
 
 
Fig. 13 is taken at a point where the bile-duct has almost left the intestinal wall. The inner circular muscular coat passes entirely over the common bile-duct at this point. At the sides are seen large masses of longitudinal muscle fibres. These are the fibres of the outer longitudinal muscle coat which
 
 
 
 
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have been pushed aside to allow passage to the common bileduct.
 
 
IV.— THE MUSCULATURE OF THE BILIARY PASSAGES IN THE RABBIT.
 
 
(rt) Gall-Madder. — The nitric acid, glycerine and water macerations show only transverse muscle fibres.
 
 
Specimens macerated in Itanvier's alcohol, and longitudinal celloidin sections reveal a muscular arrangement practically identical with that found in the dog. There seems, however, to be relatively more muscle in the gall-bladder of the rabbit than in that of the dog.
 
 
(5) Cystic duct. — Only transverse muscle fibres are seen in specimens macerated with nitric acid, glycerine and water. Longitudinal celloidin sections show the absolute amount of smooth muscle in the walls of the cystic duct to be small, and that the muscle fibres run in three directions, longitudinal, transverse and diagonal. The transverse muscle fibres are most numerous, the longitudinal fibres next in number and the diagonal fibres least of all. Connective tissue penetrates between the muscle bundles to a relatively greater degree than in the gall-bladder.
 
 
(c) Hepaiic duct. — No muscle fibres were found in macerations with nitric acid, glycerine and water. Longitudinal celloidin sections showed a very small amount of muscle. The muscle fibres follow three directions, longitudinal, transverse and diagonal. The longitudinal fibres are most niimerous. The transverse and diagonal fibres are about equal in number but there are very few of either variety. There is much connective tissue here between the muscle.
 
 
(rf) Common bile-duct. — Muscle fibres could not be detected in nitric acid, glycerine and water macerations. Longitudinal celloidin sections show longitudinal and transverse muscle fibres. The former are much more numerous than the latter. The absolute amount of muscle present in the walls of the common bile-duct is, however, very small.
 
 
(e) No extraordinary muscular arrangement was found at the place of union of the hepatic and cystic duets with the common bile-duct.
 
 
(/) The rabbit's duodenum was macerated in a mixture of nitric acid, glycerine and water. After the mucous membrane had been removed the structure represented by Fig. 14 was found. The course of the common bile-duct through the intestinal wall is parallel to that of the fibres of the inner circular muscular coat. This is just the reverse of what is found in the dog. At the first glance, one can see that the greater part of the duodenal portion of the common bile-duct is covered with muscle fibres of the inner circular muscular coat.
 
 
Some of these fibres of the inner circular muscular coat run up on the common bile-duct (see A), continue for some distance and terminate abruptly near the orifice of the duct (see R). Other fibres of the inner circular muscular coat run up on the duct, continue forward a short distance, but finally bend, some to one side, others to the opposite side (see C) and running down over the side of the duct, become continuous with the fibres of the inner circular muscular coat. The presence of some fibres of the inner circular muscular coat just under the ampulla of Vater is to be noted (see CS).
 
 
 
 
Fig. 14 also shows a sphincter muscle about the orifice of the common bile-duct (see S). This sphincter is composed of a muscular ring which surrounds the orifice of the duct. Some fibres instead of running completely around the orifice, run oflr at the side of the ring and bending forward become continuous with the fibres of the inner circular muscular coat.
 
 
The fibres of the inner circular muscular coat were next removed (except at OS}. The arrangement seen is represented in Fig. 15. The common bile-duct is seen penetrating the outer longitudinal muscular coat. The outer longitudinal muscle at the point of entrance of the common bile-duct (see A) covers some muscle fibres which run around the common bile-dTict embracing it. Immediately after penetrating the outer longitudinal muscular coat the bile-duct can be seen to be encircled with smooth muscle. Those muscle fibres nearest the point of entrance of the common bile-duct, run around or encircle the bile-duct without bending forward (see IE), but as the orifice of the duct is approached the muscle fibres which embrace the bile-duct, after running down over the side of the duct, bend forward more and more.
 
 
Thus it will be seen that in all cases, the muscle fibres described embrace the duct but with the difference pointed out above, namely, that those fibres nearest the point of entrance of the common bile-duct do not bend forward as they pass under the common bile-duct, while those nearer the orifice of the bile-duct do bend forward as they pass under it. All the muscle fibres just mentioned doubtless have a sphincter function, but if we regard the sphincter muscle of the dog we will find it homologous with the sphincter fibres S of the rabbit. Therefore, the rabbit has not only a sphincter similar to that of the dog, but it possesses also other fibres which subserve in all probability the same or a similar function.
 
 
The muscle fibres encircling the common bile-duct were now cut along the long axis of the duct. The mucous membrane of the di;ct was removed and an arrangement represented in Fig. 16 was found. At this point it is well to recall that the fibres marked CS in both Fig. 15 and Fig. 16 are those fibres of the inner circular muscular coat which lie immediately in front of and also under the ampulla. These muscle fibres (see Fig. 16, CS) run under the ampulla and there decussate irregularly, so that the fibres of the one side pass to the other side, and then curving upward and backward around the common bile-duct, embrace it. Here is seen the origin or termination of those muscle fibres which embrace the common bile-duct and bend forward as they pass under the bile-duct. Passing from this place of decussation, back toward the point of entrance of the common bile-duct into the intestinal wall, one finds the continuation of those muscle fibres which simply embrace the duct without bending forward as they pass under it (see Fig. 16, IR).
 
 
The muscle fibres of the outer longitudinal muscular coat, which lie in front of the ampulhi and under the fibres marked CS have no connection with the muscular arrangement of the duodenal portion of the common bile-duct. Further back, however, near the decussation of the fibres CS, the fibres of the outer longitudinal muscle coat seem to be more or less involved in the general decussation. Some of the fibres of the outer longitudinal muscle coat run up to the side of the bile
 
 
 
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duct, then bend around and run forward on it and at its side toward the ampulla. Others, when they reach the side of the duct, plunge inward and mingle with those bundles which embrace the common bile-duct.
 
 
Serial cross-sections of the duodenal portion of the common bile-duct of the rabbit. — Two sets of serial sections were prepared and examined. The principal fioints of interest are presented in the following cuts which are taken at difterent levels in the duodenal portion of the common bile-duct. The first figure corresponds to a section taken nearest the orifice of the common bile-duct, the others are taken at successively different levels throughout the length of the duct.
 
 
In Fig. 17, at first glance, the course of the common bileduct in the intestinal wall is seen to be parallel to the inner circular muscular fibres. The duct is situated in the submucosa of the intestine, and is seen to be surrounded by muscle bundles. The smooth muscle embraces the common bile-duct, but on each side of it some muscle fibres, instead of running under the duct, turn forward and the cross-sections of the individual smooth muscle cells indicate the fact that they have continued as a part of the fibres of the inner circular muscular coat (see JT). Between the mucous membrane of the common bile-duct and the inner circular muscular coat of the intestine are seen muscle bundles which run transverse to the course of the common bile-duct. These fibres correspond to that portion of the sphincter which runs under the common bile-duct. Comparison shows that the inner circular muscular coat (see CS) has lost few if any muscle fibres at this point. This is a fact which will have more importance in connection with the decussation of the fibres of the inner circular muscular coat. It should be noted that the fibres marked CS corresjjond to those marked CS in the macerated specimen. At this level of the common bile-duct the lumen is occupied to a considerable extent by folds of mucous membrane.
 
 
Fig. 18 has been taken at a level in the duodenal portion of the common bile-duct, further from the orifice than Fig. 17. The structures to be noted have passed from the submucosa into the tunica muscularis of the intestine. The large lumen of the common bile-duct is conspicuous (see B) and to the right, the first indication of the duct of Wirsung is met with. If we begin the description at the extreme left of the figure, just beneath the submucosa are to be seen a large number of muscle fibres in cross-section (see CI). These are present, but in diminished number throughout more than one-half the breadth of the section. These fibres belong to the inner circular muscular coat of the intestine which at this point does not quite cover the bile-duct.
 
 
Toward the extreme right are seen large bundles of transversely cut muscle fibres (see CF). Running to join these last named bundles, are muscle fibres cut diagonally and longitudinally. The longitudinally cut muscle fibres apparently arise from the outer longitudinal muscle coat of the intestine and running over the common bile-duct finally bend around and become continuous with the transversely cut inner circular muscular fibres CI. If we again examine the extreme left of the figure, there are to be seen fibres cut longitudinally (see LI) immediately under the inner circular muscle coat. These represent the outer longitudinal muscular coat. In this par
 
 
 
ticular section there is a division of the fibres of the outer longitudinal muscular coat. Some pass over the duct and then bend around as described above to become continuous further forward with the inner circular muscle coat. Others run as if to pass under the bile-duct but suddenly terminate. In their place one sees transversely cut muscle fibres which extend for a considerable distance to the right and then suddenly stop (see LF). Where these fibres (LF) stop we find longitudinally cut muscle which represents the outer longitudinal muscle coat of the intestine (see LI). Tlie explanation of the structures last mentioned is probably to be found in the circumstance that the muscle fibres of the outer longitudinal muscular coat on either side of the long axis of the common bile-duct bend around and, converging, run forward in the direction of the ampulla of Vater. The fibres marked LF represent those muscle bundles which run forward. The transversely cut muscle fibres marked CS represent fibres of the inner circular muscle coat. These are the continuation of the fibres marked CS in Fig. 17 and correspond to the CS fibres of the macerated specimen. At this level the decussation of the inner circular muscle fibres as described in the macerated specimen ought to be seen, and as a matter of fact this decussation corresponds to those muscle bundles of the figure which have not already been described. They run up on the right as diagonally cut muscle. The segments of diagonally cut muscle show that successive bundles have been cut. Running under the bile-duct is another large muscle bundle. To the left of the bile-duct are still other bundles of diagonally cut muscle. I believe that all these bundles come from the CS fibres of Fig. 17 and that their particular arrangement is due to the decussation and subsequent embracing of the common bile-duct by them. This arrangement will be better understood by referring to the macerated specimen. This series of sections did not siiow muscle running between the lumen of the common bile-duct and the lumen of the duct of Wirsung, to form a double sphincter. Examination of the second set of serial sections, however, at about the same level as that represented by Fig. 18, proved this structure to be present. Here were found muscle bundles arising on the outer side of the common bile-duct from the region of the decussation of the inner circular fibres and running inward between the common bile duct and the duct of Wirsving they finally were seen to terminate by blending with fibres on the inner side of the common bile-duct. These lastnamed muscle bundles had origin amongst the decussating fibres of the inner circular coat and then curved around the common bile-duct to the inner side of the same and finally blended in part with those fibres which have been described as running between the common bile-duct and the duct of Wirsung.
 
 
Fig. 19 is taken at a level still more remote from the duodenal papilla. Passing from the inner side of the intestine toward the outer side we see the mucosa of the intestine, the inner circular muscular coat of the intestine (see CI) and the outer longitudinal muscle coat (see LI). The lumen of the common bile-duct is prominent (see B) and to the right that of the duct of Wirsung. Around the bile-duct longitudinally cut muscle bundles are arranged. They embrace the duct and represent (1) independent muscle bundles embracing the duct
 
 
 
 
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and (2) fibres of the outer longitudinal muscle coat (shown to the extreme right in the drawing) which have run up on the surface of the bile-duct.
 
 
Outside the bile-duct and the muscle bundles embracing it are seen muscle fibres cut transversely. On the left, diagonally cut bundles are found running toward this transversely cut muscle. These diagonal bundles represent those fasciculi of the outer longitudinal muscle coat which have curved around at the side of, and also on, the common bile-duct and then have run forward toward the ampulla of Vater (see LF.)
 
 
In Fig. 20 the typical intestinal wall is shown. The common bile-duct is outside the intestinal wall and a few longitudinal and diagonal muscle bundles are to be seen in its wall. These must be regarded as stray fibres running up on the bileduct from the intestine and not as fibres of the proper fibromuscular tunic of the common bile-duct.
 
 
v.— THE MUSCULATURE OF THE BILIARY PASSAGES IN MAN.
 
 
(rt) (fall-bladder. — What has been said concerning the gallbladder of the dog may be repeated of the gall-bladder of man. Fig. -21.
 
 
(5) Cystic duct. — Macerations in a mixture of nitric acid^ glycerine and water showed the arrangement of smooth muscle to be plexiform. Longitudinal celloidin sections of the cystic duct demonstrated smooth muscle running in three directions, viz. transverse, longitudinal and diagonal. Fig. 32. The transverse bundles are most numerous ; the longitudinal and diagonal bundles are about equal in number. In that portion of the cystic duct nearest the neck of the gall-bladder, the amount of muscle is considerable, but this gradually diminishes in amount as .the common bile-duct is approached. At the junction of the cystic, hepatic and common bile-duct the quantity of muscle present is very small. These sections also show muscle fibres in those folds of the cystic duct which are known as the valves of Heister. The fact that muscle is present in these folds has been noted before by only one person (A. MacAlister) and he does not undertake to describe the course pursued by the muscle bundles.
 
 
In a set of serial longitudinal sections of the entire human cystic duct, I have found the arrangement represented by the following schema. Fig. 23. This schema, based upon study of the serial sections, shows :
 
 
(1) That the transverse muscle bundles of the cystic duct are not limited to the wall proper, but at the level of the valves of Heister also run around in the valve in a circular direction. It is just as if the wall of the duct had been invaginated at this level and as a result the circular muscle fibres were carried out into the fold thus formed.
 
 
(2) That most of the longitudinal muscle bundles of the cystic duct continue down the duct without entering the valve, but still there are some of these bundles which (having reached the level of the valve) bend around at almost right angle and run out into the fold.
 
 
(3) We have no evidence that the diagonal fibres take any part in the musculature of the valves of Heister.
 
 
We believe, therefore, that the transverse muscle bundles predominate in the valves of Heister. Those valves nearest the
 
 
 
 
common bile-duct are quite small and either contain very little muscle or none at all.
 
 
((:) Hepatic duct. — The description of the rabbit's hepatic duct applies without any addition to the hepatic duct of man. Pig. 26.
 
 
id) Common bile-duct. — The muscle fibres could not be detected with certainty in nitric acid, glycerine and water macerations. Longitudinal celloidin sections revealed a small amount of muscle. The direction followed was not only transverse but also longitudinal and diagonal. The number of transverse and longitudinal fibres was about equal; the oblique muscle fibres were least numerous. Much connective tissue was found between the muscle fibres. Fig. 27.
 
 
(c) Point of union of cystic, hepatic and common bile-ducts. — Each duct preserved its typical structure.
 
 
(/) Preliminary to the description o{ the duodenal portion of the human common bile-dtict, it will be well to state that many individual variations in structure occur but that these variations do not alter the general anatomical bearing of this region.
 
 
The following drawings have been made from a typical specimen macerated in a mixture of nitric acid, glycerine and water.
 
 
Fig. 28 shows the entrance of the common bile-duct B and the duct of Wirsuug W into the intestinal wall. AVe see a simple separation of the fibres of the outer longitudinal muscular coat of the intestine LI. The common bile-duct and the duct of Wirsung pass through this separation. At F we find muscle fibres arising from the outer longitudinal muscular jcoat. These fibres run up on the common bile-duct and becoming gradually less and less marked, finally disappear. This arrangement is bilateral. The fibres marked IE represent some bundles of muscle which (shown in Fig. 30, IE) form an indej)eudent ring of muscle around the common bileduct between it and the duct of Wirsung.
 
 
At H are seen muscle fibres which run almost entirely around the duct of Wirsung, but as these fibres aj)proach that side of the pancreatic duct nearest the common bile-duct, they turn abruptly and run up on the duct of Wirsung in a longitudinal direction. They gradually diminish in volume as they ascend the duct. This structure is bilateral. See also Fig. 30, H.
 
 
Fig. 29 represents the structures seen upon removal of the mucous membrane from the intestinal wall in the region of the duodenal papilla. The inner circular muscular coat of the intestine is represented by CI. The first point to demand attention is the penetration of the inner circular muscular coat by the common bile-diict. At the spot of penetration there is a simple separation of the muscle bundles of the inner circular nmscle coat. It should be noted that the human specimen differs from the arrangement found in dog. It will be remembered that in the latter animal, the inner circular muscle coat forms a tube-like structure which embraces the common bile-duct for a considerable distance. In man the common bile-duct plunges immediately through the muscle layer which composes the inner circular muscular coat.
 
 
At *S are bundles of muscle running around the common bile-duct (see also Fig. 30, S). These are iudepeudent rings of muscle which embrace the duct. Now, if we look further
 
 
 
 
 
 
 
><^£-^ W A^--'^-fe5^^s:
 
 
 
 
 
Fig. 1. — Loiiffitudiual section of the sall-bladik-r Of doff, x 30.
 
 
 
 
Fk;. 'Z. — Louffitudinal section of the cvstic duct of dog. x 30.
 
 
 
 
Fig. 3. — Longitudinal section of the cystic duct of dog, showing the musculature of a Heisterian valve, x 30.
 
 
 
 
 
Fig. 4. — Longitudinal the hepatic duct of dog.
 
 
 
 
 
Fig. T.--MM(eiatcd duodennl portion of the coniniciii bile-duct of dog. Part of the circular muscular coat of the intestine has been removed. X 4.
 
 
 
 
 
Fig. h. — Longitudinal sect: the common bile-duct of dog.
 
 
 
 
 
Fig. 8. — Macerated duodenal portion of the common bile-duct of dog. The relation of the common bile-duct to the longitudiual muscular coat of the intestine i.s shown. x4.
 
 
 
 
 
Fiti. C). — Macerated duodenal portion of the common bile-duct of dog. The mucous membrane, muscularis mucosEe and submucosa of the intestine have been removed, x 4.
 
 
 
 
 
 
 
 
^\
 
 
 
 
 
 
 
^^^>-^
 
 
 
 
 
Fig. 0. — Cross-section near the oritice the common bile-duct of dog. x 30.
 
 
 
 
 
 
 
 
if the duodenal portion of
 
 
 
TuE Johns Hopktxs IlosprrAi, Bulletin Nos. 90-91.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fio. 10.— Cross-sectiou somewhat removed from the orifice of the duodenal portion of the common bile-duct of dog. x 30.
 
 
 
 
Fio. 11. — Cross-section near the middle of the duodenal portion of the common bile-duct of dog. x 30.
 
 
 
 
 
 
 
 
 
 
oooooooo/Kv
 
 
 
 
 
 
 
 
-Cn\v -^ /^ ^ "^
 
 
 
 
 
 
 
Fig. 13. — Cross-section somewhat removed from the middle of the duodenal pnrtion of the commim bile-duct of dng. x 30.
 
 
 
 
 
Fig. 13. — Cross-section at the entrance of the common bile-duct into the intestinal wall of dosf. x 30.
 
 
 
 
 
-"ll'I'Wit
 
 
 
 
-±1 'J
 
 
 
 
J"iG. 14. — Macerated duodenal portion of the common bile-duct of rabbit. The mucous membrane, muscularis inucosie and submucosa of the intestine have been removed. >:4.
 
 
 
 
Fig. 15. — Macerated duodenal portion of the common bile-duct of rabbit. The greater ]iart of the circular muscular coat of the intestine has been removed, x 4.
 
 
 
 
Fig. 10. — Macerated duodenal (lortiou of the common bile-duet of rabbit, showing the distribution of the CS and /if flbres. x 4.
 
 
 
 
llrndrickKOH, <lcl.
 
 
 
 
 
 
Fig. 17. — Crnss-sectiou near the orifice of tlie duodenal portion of the eommiin bile-duct of rabbit. x 40.
 
 
 
 
Fio. IS. — Cross-section somewhat removed from the orifice )f tlif duodenal portion of the common bile-duct of rabbit. x 40.
 
 
 
 
 
 
Fi<;. 19. — Cross-section near the (ntrauee of the common bile-duct Fig. 20. — Cross-section at flic entrance of the common bile-duct
 
 
into the iutestiual wall of rabbit. x 40. into the intestinal wall of rabbit. x 40.
 
 
 
 
 
 
Fig. 21 Longitudinal section of
 
 
the gall-bladder of man. x 30.
 
 
 
 
BendrickBon, del.
 
 
 
 
 
Fig. 23. — Longitudinal section of the cystic duct of man. x BO.
 
 
 
 
 
Lerei at which Fig. 34 is taken. Fig. 3.5.
 
 
 
 
Fig. 33. — The cystic duct of man, showing the Ileisterian valve ; also, a diagram of the musculature of the Ileisterian valve.
 
 
 
 
 
Fig. 34. — Oue of the longitudinal serial sections of the cvstic duct of man. See Fig. 23. x30.
 
 
 
 
 
Fui. 3(1. — Louifitudinul section of thehei.iatio duct of man. x oO.
 
 
 
 
 
Fig. 39. — Macei-ated duodenal portion of the common bile-duct of man. The mucous inembraue, muscularis mucosa aud submucosa of the intestine have been removed, x o.
 
 
 
 
 
Fiii. 3."). — One of the longitudinal serial sections of the cystic duct of man, showing the muRCuUitnre of a valve of Heister. See Fig. 33.
 
 
 
 
 
Fjg. 37. — Longitudinal section of the common bile-duct of man. x 30.
 
 
 
 
 
Fig. 28. — Macerated duodenal portion of the common bile-duct of man. The relation of the common bile-duct and the duct of Wirsung to the longitudinal muscular coat of the intestine is shown. x 5.
 
 
 
 
 
Fig. 30. — Macerated duodenal portion of the common bile-duct of man. AH of the intestinal coats have been removed, x 5.
 
 
 
 
 
Fig. 81. — Cross-section near the orifice of the duodenal portion of the common bile-duct of man. x 30.
 
 
 
 
 
Fig. 32.— Cross-section at the cntriiiic.' of the common bile-duct into the inlestinal wall of man.
 
 
 
 
September-October, 1898.]
 
 
 
 
JOHNS HOPKINS HOSPITAL BULLETIN.
 
 
 
 
231
 
 
 
 
back on the common bile-duct, near the point at which it penetrates the inner circular muscular coat, we observe muscle bundles 2!' which do not run entirely around the duct. These muscle bundles are very intimately mixed with the independent muscle rings which completely embrace the duct. The former, however, upon reaching the level of the inner circular muscle coat, turn abruptly forward and under the bile duct, and after running for some distance toward the duodenal papilla finally end in the connective tissue of the submucosa of the intestine (see also Fig. 30, JT). This arrangement is bilateral. The drawing shows that this arrangement of muscle about the common bile-duct begins at a point before the duct penetrates the inner circular muscular coat. In this particular specimen, a muscle bundle of the inner circular muscular coat curves around and becomes continuous with the fibres marked X. It may be well to note that the X fibres did not terminate in all cases according to this description. In several cases these fibres, after turning forward and under the common bile-duct, decussated with similar ones from the opposite sicie and after such decussation became continuous with the fibres of the inner circular muscular coat of the intestine. In one case the X fibres after turning forward suddenly plunged through the inner circular muscle coat and became continuous with the fibres of the outer longitudinal muscle coat of the intestine. ,
 
 
Another point observed in some specimens but not in this one is worthy of mention. In some specimens after dissecting away the <S' fibres, a few longitudinally and diagonally disposed fibres were seen. These had origin in those fibres of the outer longitudinal and inner circular muscle coat which lie over the common bile-duct when viewed as in Fig. 29. Finally in Fig. 29 a bundle of muscle fibres K can be seen on each side of the common bile-duct running parallel with it. These bundles arise on the surface of the common bile-duct (Fig. 30, K} and are covered by the F fibres of Fig. 28. In this case they run forward from under the inner circular muscular coat (see Fig. 29, K) and bend around beneath the common bile-duct, becoming continuous with each other, thus forming a loop around the duct of Wirsung, Fig. 30, K. In other specimens these ^fibres originate in the same way but terminate by running under the common bile-duct and decussating there with similar fibres from the opposite side.
 
 
Fig. 30 shows the muscular arrangement about the end of the common bile-duct and the duct of Wirsung after all fibres of the outer longitudinal and inner circular muscle coats have been removed. The common bile-duct and the duct of Wirsung have been drawn in the same position as they occupied in Fig. 28, but removal of the muscular coats of the intestine permits of a view of the various structures in profile. All the structures here shown have been described more or less fully under Figs. 28 and 29.
 
 
After an examination of serial cross-sections of the duodenal portioii.of the human common bile-duct, we have selected two of them for illustration since they represent the principal points. The first figure (Fig. 31) is taken near the level of union of the common bile-duct with the duct of Wirsung. The structures of interest are situated in the submucosa of the intestinal wall. The large opening — to the right — is the lumen of tlie ductus
 
 
 
 
communis choledochus; the narrow slit — to the left — represents the collapsed lumen of the duct of Wirsung. At the point X, muscle bundles cut in cross-section and sometimes diagonally are seen. These bundles represent those fibres of the sphincter muscle which do not run entirely around the common bile-duct. They become detached at the side of the duct from the sphincter proper and turn forward. These bundles then run forward, under the common bile-duct and gradually approach the bundles of the opposite side ; they finally end free in the connective tissue of the submucosa near the orifice of the common bile-duct. These bundles correspond to the X fibres of the macerated specimen. It is probable that the K fibres of the macerated specimen are also included among the bundles described above, but we have not been able to distinguish them in the sections from the others.
 
 
The remaining bundles of muscle about the common bileduct belong to the sphincter muscle proper : they correspond to the S fibres of the macerated specimen. A bundle of muscle fibres cut longitudinally is seen running between the lumen of the duct of Wirsung and that of the common bile-duct. I consider this to be a bundle of the sphincter muscle and believe that it corresponds to the "double sphincter" arrangement found in the dog and rabbit, and described above.
 
 
The second section (Fig. 32) represents the common bileduct just before it has penetrated the nii;scle coats of the intestine. Around the common bile-duct are seen muscle bundles cat transversely. These represent the K fibres of the macerated si:iecimen. No muscle fibres arising from the outer longitudinal muscle coat and running up on the common bileduct can, however, be demonstrated in this specimen.
 
 
VI.— CONCLUSIONS.
 
 
The principal results of this research may be briefly summed up in tabular form; under the various heads only the most general findings are mentioned.
 
 
 
 
(a) Gall-bladder
 
 
 
 
(b) Cystic duct
 
 
 
 
Transverse*
 
 
Longitudinal
 
 
Diagonal
 
 
Transverse
 
 
Longitudinal
 
 
Diagonal
 
 
 
 
Transverse
 
 
Longitudinal
 
 
Diagonal
 
 
Transverse
 
 
Longitudinal
 
 
Diagonal
 
 
 
 
Transverse
 
 
Longitudinal
 
 
Diagonal
 
 
Transverse
 
 
Longitudinal
 
 
Diagonal
 
 
 
 
Valves of Heister.
 
 
 
 
The transverse fibres of the cystic duct run around in the valves of Heister in a circular direction. The longitudinal fibres bend at a right angle and run out into the valve. Diagonal fibres apparently do not enter the valves of Heister.
 
 
 
 
(c) Hepatic duct Longitudinal
 
 
 
 
Transverse
 
 
Longitudinal
 
 
Diagonal
 
 
 
 
Transverse
 
 
Longitudinal
 
 
Diagonal
 
 
 
 
'These terms are used with reference to the long axis of the duct.
 
 
 
Transverse
 
 
(d) Common bile- Longitudinal
 
 
duct Diagonal
 
 
(e) Place of union Each duct pre of the cystic, served its typihepatlc and cal structure ;
 
 
the wall of each gradually merging into that of the others.
 
 
 
 
common bile-ducts
 
 
 
 
(f) Duodenal por tion of the Common bile-duct
 
 
 
 
A sphincter muscle exists.
 
 
 
 
Transverse Longitudinal
 
 
 
 
Each duct preserved its typical structure ; the wall of each gradually merginto that of the others.
 
 
 
 
A sphincter muscle exists.
 
 
 
 
Transverse
 
 
Longitudinal
 
 
Diagonal
 
 
Each duct preserved its typical structure ; the wall of each gradually merging into that of the others.
 
 
A sphincter muscle exists.
 
 
 
 
VII.— INDEX LETTERING OF THE FIGURES.
 
 
B, Common bile-duct.
 
 
01, Circular muscular coat of the intestine.
 
 
CS, Fibres of the circular muscular coat of the intestine which have a distribution indicative of a secondary sphincter.
 
 
D, Diagonal muscle.
 
 
E, Epithelium.
 
 
 
 
QB, Next to gall-bladder.
 
 
IB, Independent rings of muscle embracing the common bileduct.
 
 
K, Fibres which arise on the common bile-duct and run around the duct of Wirsung to become continuous with similar fibres of the opposite side.
 
 
L, Longitudinal muscle.
 
 
LI, Longitudinal muscular coat of the intestine.
 
 
LF, Fibres of the longitudinal muscular coat of the intestine which turn and run forward toward the ampulla of Vater.
 
 
M, Mouth of the common bile-duct.
 
 
MI, Mucous membrane of the intestine.
 
 
JV^, Muscle bundles which have origin in the median line of the common bile-duct and afterwards run forward parallel with the long axis of the duct.
 
 
NB, Next to common bile-duct.
 
 
S, Sphincter fibres.
 
 
81, Submucosa of the intestine.
 
 
T, Transverse muscle,
 
 
W, Duct of Wirsung.
 
 
X, Those fibres of the sphincter which become detached latersjly and run down the intestine.
 
  
 
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Mall FP. The lobule of the spleen. (1898) Johns Hopkins Hospital Bulletin 9: 218-.

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The Lobule of the Spleen

Franklin Mall (1911)
Franklin Mall

By Franklin P. Mall.

From the Anatomical Laboratory, Johns Hopkins University.


Introduction

When the whole vascular system of the spleen is studied in connection with the trabecular system, it is found that the two together outline distinct masses of spleen pulp about one millimeter in diameter. These may easily be likened to the liver lobules, and for this reason I name them the lobules or the anatomical units of the spleen.

If a piece of fresh spleen is washed out by crushing it between the fingers in flowing water, it is found that the trabeculse and veins outline spaces which were filled with pulp. They are best demonstrated by macerating the whole spleen in water at ordinary room temperature until the pulp is very soft. Then, by cutting off the small end of the organ, the debris may be washed out, leaving the capsule, larger veins and trabeculffi. A specimen obtained in this way may then be stained with acid fuchsin, washed with alcohol, distended and dried. Then with transmitted light the lobules are plainly seen as vesicles immediately below the capsule. By first injecting the spleen with either colored celloidin or agar-agar before macerating, the relation of the arteries and veins to the lobules can be determined. This is possible because neither the celloidin nor agar-agar is destroyed by the process of maceration. Thick sections made from such specimens may be immersed in xylol or mounted in Canada balsam.

It is found by studying numerous specimens of this sort, as well as those made by injecting cinnabar into the arteries and ultramarine blue into the veins, that the artery always penetrates the lobule and passes along its center, while the vein is intimately related to the trabecule and remains on the periphery of the lobule. In the case of the lobules lying immediately below the capsule, the artery enters the side as far away from the capsule as possible, as shown in the figure. The end of the lobule at which the artery enters I shall term the proximal side, while that opposite will be designated the distal side of the lobule. The deeper lobules of the spleen, then, have a distinct relation to the artery and not to the capsule. The Malpighian corpuscle usually lies in the proximal end of the lobule, but, in case it is very large, it may distend the lobule and cause it to bulge.

On an average there are 80,000 lobules in the spleen of a dog weighing 10 kg. In smaller spleens there may be as few as 25,000, while in larger spleens there may be 200,000. In all cases they are clustered together around the terminal branches of the artery in the same manner as the lobules of the lung are around the bronchus and the lobules of the liver around the hepatic vein. In order to understand the structure of the spleen it is necessary to study one lobule only, and for its anatomy the relations of the lobules to one another.



Fig. 1 Diagram of the Lobule of the Spleen. A, artery in the centre of the lobule; r, interlobular vein within the interlobular trabeculie ; Tr, intralobular trabecula- ; L, JIalpiijhian follicle ; C, intralobular collecting vein ; P, intralobular vein plexus which surrounds the pulp cords or histological units; Am, ampulla of Thoma.


The accompanying figure is a diagram of an average lobule drawn to scale. In no case can a picture like this be gotten from a single section, as the artery and two veins are never in the same plane. Moreover, the branches from the artery, as well as those from the vein, radiate from the main stem and pass in all directions. Practically all of the interlobular veins are covered by interlobular trabeculse, but tbere are numerous interlobular trabeculse which are solid. In the periphery of each lobule there are three main interlobular trabeculag, each of which sends three branches into each of the three surrounding lobules. The intralobular trabecule communicate with one another within the lobule, thereby dividing the lobule into about ten compartments. The relation of the veins to the lobule is much like that of the trabeculas. In fact, it is the relation of the trabecule to the veins which makes the lobule. The large veins of the spleen cannot be said to lie within the trabeculse, although their walls are thick, are continuous with the trabeculas and give rise to them. The points which mark the separation of the smaller veins from the trabeculse mark the boundary of the lobule (see diagram). As the venous branches leave the lobule they are at first independent of the intralobular trabecule, but near their exit they are related to them. The intralobular collecting veins also aid to divide the lobule into the ten parts, spoken of above. Of course the artery is distributed to the lobule from a direction opposite to that of the veins. The tendency is for veins and arteries of the same order to remain as far separated from one another as possible. The central artery of the lobule gives rise to .about ten branches, each of which passes into one of the ten compartments of the lobule and through its centre. All of the above can be demonstrated best with granular infections, thick sections and low magnification.

If an interstitial injection of the spleen is made with an aqueous solution of Prussian blue, or if the blue is injected into the vein, it is found in either case that the venous plexus of the lobule is completely filled. This plexus is indicated in the figure giving its relation to the surrounding structures. It divides the spleen pulp into small areas or the histological units as I call them. In fact, however, these areas are not isolated, but communicate with one another as do the cavities of a sponge. Since the histological units run together to form cords of spleen tissue, I term them collectively pulp cords. Thick sections which leave the venous plexus intact show the optical section of the pulp cords or the histological units, while very thin sections cut the venous plexus and demonstrate the pulp, cords. The terminal arteries ramify in the pulp cords and along their course, give off numerous small branches which end in a dilatation, the ampulla of Thoma. The beginning of the ampulla always lies in the centre of a pulp cord. As a rule a number of the minute branches arise from each terminal artery and radiate in all directions. I have been able to obtain complete injections of the vascular system of the spleen only after the organ has been distended to its maximum by ligating the vein half an hour before killing the animal or by making an artificial oedema with gelatin by injecting it into the veins. By both methods all the intercellular spaces within the pulp cords become enormously distended. In spleens prepared in either of the above ways the ampulla? and their communications with the veins may be filled by injecting an aqueous solution of Prussian blue into the artery. If carmine or some such fluid is used it will only add another color to the fluids in the pulp spaces. The blue, however, precipitates easily and with it, it is often easy to obtain complete injections. The specimen is made still better if the venous plexus is marked by injecting chrome yellow into the vein before injecting the blue into the artery. The gelatin-spleens are best cut on the freezing microtome and mounted in glycerine, as alcohol causes too much shrinkage of the gelatin. The injections show that the ampullffi have a tendency to communicate with amptillje from neighboring arteries, while other branches comnnmicate directly with the veins. Yet judging from the amount of extravasation which is always present the walls of the ampullar must be very porous.

Carmine gelatin injected into either the artery or vein will cause an CBdema of the pulp; in case it is injected into the artery it will ultimately run out of the vein, while when injected into the vein it will never run out of the artery. When cinnabar is injected into the artery, the greater part of it passes directly over into the vein, while a small portion of the granules pass into the tissues. When it is injected into the vein a considerable quantity passes into the intercelltilar spaces of the ptilp cords, showing that the walls of the vein are pervious. Solutions of nitrate of silver injected into the artery show that the endothelial coat becomes incomplete at the beginning of the ampulla. The first two-thirds of the amptilla are lined with spindle-shaped cells lying upon a delicate framework of reticulum. Throughout the last third, at the junction with the vein, no cell boundaries can be demonstrated, nor can this portion of the amptilia be injected from the vein. In fact it appears as if this portion of the ampulla were cut up by fibrils of reticulum passing across it. Silver injected into the veins shows that the complete layer of cells ends at the point of junction of the intralobular plexus with the intralobular collecting veins. Throughout the plexus the cell walls are incomplete and the endothelial cells are spindle-shaped, the space between them being large enough to allow cinnabar granules to pass easily, tiltramarine blue granules with difficulty, and chrome yellow granules not at all. The openings in the veins are largest in the neighborhood of the Malpighian follicles.

The reticulum extends throughout the lobule, supplies the framework for the ampullse and the venous plexus, and is continuous with the reticulum of the lymph follicles surrounding the arteries. Its arrangement is such that an cedema distends the lumina of the veins out of proportion to those of the pulp spaces. The reticulum is very delicate and elastic. It can be stretched to double its length and when relaxed it will return to its former shape. It is easily destroyed with acid or with alkali, and is digested with pancreatin. This last reaction makes of it a new variety of reticulum. While this reticulum is so delicate and easily destroyed, the reticulum of the trabeculse and capsule is most resistant. In fact, it is more resistant than that of the lymphatic gland or of the mucosa of the intestine. We have therefore within the spleen two extremes of reticulum, the most resistant and the least resistant.

The microscopic anatomy shows that the ampulla} and venous plexus have very porous walls which permit fluids to pass through with great ease and granules only with difficulty. In life the plasma constantly flows through the intercellular spaces of the pulp cords, while the blood corpuscles keep within fixed channels. Numerous physiological experiments which I have made corroborate this view.

A more detailed account of the facts enumerated above, together with illustrations, is being prepared for publication.




Cite this page: Hill, M.A. (2020, March 29) Embryology Paper - The lobule of the spleen (1898). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_The_lobule_of_the_spleen_(1898)

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