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| CONTRIBUTIONS TO EMBRYOLOGY, No. 57.
| | #REDIRECT [[Paper - On the development of the lymphatics in the stomach of the embryo pig (1921)]] |
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| ON THE DEVELOPMENT OF THE LYMPHATICS IN THE
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| STOMACH OF THE EMBRYO PIG,
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| BY JAMES R. CASH,
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| From the Anatomical Laboratory, Johns Hopkins University.
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| With three plates and three text-figures.
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| ON THE DEVELOPMENT OF THE LYMPHATICS IN THE
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| STOMACH OF THE EMBBYO PIG,
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| The work of Dr. Mall (1896) on the anatomy of the lymphatics of the wall
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| of the stomach has established the plexiform arrangement of these vessels and their
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| relation to the other structures of this organ. By dissecting the stomachs of dogs in
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| which the lymphatics had been injected, and by reconstructions of such dissections,
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| the entire organ was shown to be supplied with four definite, homogeneous plexuses.
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| The most delicate of these, and the one most intimately related to the lining of the
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| stomach, is the mucosal plexus. It lies in the mucosa at the base of the gastric
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| glands just external to the muscularis mucosse and receives branches which lie
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| between the glands and extend out as far as the gastric pits. Owing to the delicacy
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| of these vessels and the fact that valves prevent their injection from the main
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| plexus of the submucosa, any attempt at complete injection is attended with much
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| difficulty. As a matter of fact, the mucosal vessels can be injected in the adult
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| only by direct puncture, which means that the needle must actually pass through the
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| muscularis mucosa? and enter the narrow zone between it and the base of the gland ;
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| it can be readily seen that such an exact placing of the needle occurs only by chance.
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| However, th( best specimens obtainable indicate clearly that the lymphatics
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| between the glands communicate directly with this delicate, homogeneous plexus
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| lying at the base of the glands of the mucosa.
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| Proceeding through the wall of the stomach toward its serous surface, the first
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| plexus of the submucosa is encountered. This consists of a single layer of lym-
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| phatics, just outside the muscularis mucosse, and forms the connecting link between
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| the mucosal plexus, just described, and the main plexus of the submucosa, the
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| principal plexus of the wall of the stomach. This main plexus is a dense mass of
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| vessels which practically fills the submucosa and is composed of several layers of
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| large, tortuous, thickly arranged lymphatics. Springing from it are numerous
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| slender vessels which traverse the muscular coats of the stomach, forming a coarse
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| plexus between them, and are gathered together on the surface of the stomach into
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| the subserous plexus, a dense, single layer of lymphatics situated just beneath the
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| peritoneal covering of the organ.
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| The work of Dr. Mall extended that of Sappey, Teichmann, and Loven. It
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| may be seen, therefore, that the anatomy of the lymphatic vessels in the wall of
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| the adult stomach is well known. The pathways of lymphatic drainage from this
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| organ, however, are not so clearly understood. All investigations along this line
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| have consisted in partial injections of the adult stomach. In the present experi-
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| ments the direction of flow of the injection mass from different points was noted and
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| from the information so gained the direction of normal lymphatic drainage, in vivo,
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| is inferred.
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| The most extensive work of this kind has been done by Cuneo. By injecting
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| colored substances directly into the main plexus of the submucosa, and watching its
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| LYMPHATICS IN THE STOMACH OF THE EMBRYO PIG.
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| the stomach. After Cunoo, 1902.
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| 1. The coronary or principal current.
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| 2. Right gastro-epiploic current.
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| 3. Splenic current.
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| flow over the wall of the stomach and its appearance in regional lymphatic glands, he
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| has obtained a very good general idea of this question. As a result, he felt justified
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| in dividing the stomach into three main lymphatic zones (Poirier and Cuneo, 1902).
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| These arbitrary zones are shown in text-figure 1. The arrows show the direction
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| of the flow of lymph from the different parts. Zones 1
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| and 2 drain the glands of the lesser curvature, while the
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| flow from zone 3 goes to the hilum of the spleen and
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| then on to the pre-aortic glands. It is to be noted that
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| no drainage is indicated by way of the duodenum.
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| Cuneo states that most of the lymph flows directly
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| toward the lesser curvature and passes through glands
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| situated in this region, whose efferent ducts drain into
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| the pre-aortic lymph-nodes just anterior to the cy sterna
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| chyli. Zone 1 represents this area. In the area desig-
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| nated as zone 2 the flow of lymph is toward the pylorus, TEXT . FIQ . 1 ._ Lymphatic tcrritoricn ,
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| as indicated, but passes posterior to it to the glands
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| of the lesser curvature. From zone 3 lymph passes
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| through vessels in related folds of peritoneum, to the
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| hilum of the spleen and from there to the pre-aortic lymph-nodes.
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| As one looks at a cross-section of a stomach wall in which the lymphatics have
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| been injected, the extreme vascularity of the organ becomes immediately apparent.
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| The plexuses are so dense, permeate the entire organ so thoroughly, and are so rich in
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| their anastomoses that definite lymphatic zones and fixed points of drainage for the
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| different regions are anatomically difficult to establish. The more conservative
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| and apparently more accurate view is that the wall of the stomach contains four
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| complete lymphatic plexuses, in open communication with each other and through
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| which lymph may flow, peripherally, in any direction. It is quite difficult to con-
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| ceive of such dense, homogeneous plexuses being divided into any zone-like arrange-
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| ment. Certainly, the lymph will leave the stomach by way of the nearest and most
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| accessible avenue of exit, and injections made around the regions toward which
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| lymphatic flow occurs will apparently find zones in which most of the flow takes
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| place in a given direction; but in view of the complex nature of the vessels within
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| the wall of the stomach the accuracy of areas found in this manner becomes very
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| doubtful. Thus it is evident that our knowledge of the gastric lymphatics is not yet
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| complete. Such methods as those mentioned are sufficient only for the formation
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| of general ideas and beyond this point any statement is speculative. As yet, no
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| work has been done on the embryology of these vessels. To resolve such dense
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| lymphatic plexuses into their component parts by injection after they are fully
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| developed is obviously impractical. By a study of their origin and development it
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| was hoped that more accurate views might be adopted for the lymphatic drainage
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| of this organ, and it was with this idea that the present investigations in embryo
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| pigs were undertaken.
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| By the method of injection, embryos can be studied in various stages before
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| the lymphatic development is complete. In this way the origin of the vessels, the
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| LYMPHATICS IN THE STOMACH OF THE EMBRYO PIG. 5
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| points at which they reach the stomach, their manner of growth, their anastomoses,
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| and finally the relation of the gastric lymphatics to the lymphatics of other organs
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| can be observed. Embryos 40, 60, 80, and 120 mm. in length were used. Those
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| up to 90 mm. were injected through the retroperitoneal sac, or its remains, the
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| large lymphatic plexus of vessels between the Wolffian bodies. In the embryos
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| measuring over 90 mm. the injections were made directly into the submucosal
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| plexus at the lesser curvature, since valves and nodes, forming at this age, prevent
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| retrograde injection of the organ from the retroperitoneal sac. In such a study it
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| would be very helpful to have complete injections of the lymphatics of the adult
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| stomach and its surrounding organs, but the valves and nodes along the course of
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| the vessels act as effective barriers to extensive injections. For a successful
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| injection the embryo must be fresh, preferably with the heart still beating. Hypo-
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| dermic syringes of 1 c. c. capacity with fine needles (No 28), were used for inject-
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| ing. The best specimens were obtained with a saturated aqueous solution of
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| Berlin blue as the injection mass. Most of the material was cleared in oil of winter-
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| green by the Spalteholz method. Thick microscopic sections were cut to show the
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| progressive development of the plexuses within the stomach wall and the course of
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| the vessels which traverse the ligaments of the spleen. The actual technique of
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| injecting the retroperitoneal sac has been described by Baetjer (1908) in his work
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| on the morphology of that structure and need not be repeated here.
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| In their development the lymphatics of the stomach pass to it by way of its re-
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| lated folds of peritoneum. Therefore, a clear idea of the relation of these folds to
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| the stomach, as well as to the points of origin of the lymphatic trunks which invade
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| it, is imperative for an understanding of the development of these vessels. As the
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| relations of this part of the peritoneum in the pig are slightly different from those in
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| the human body, a brief description of them is necessary. The dorsal mesogastrium
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| which later forms the great omentum, contains the spleen between its layers. The
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| spleen lies ventralward, close along the greater curvature of the stomach, and has
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| two ligaments. The first of these is the gastro-splenic, that part of the omentum
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| connecting the spleen with the greater curvature of the stomach. The second is
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| the splenic ligament, that part of the omentum which forms the posterior wall of
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| the omental bursa and from the hilum of the spleen is continuous with the perito-
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| neum covering the Wolffian body, the general mesentery of the intestine and the
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| mesentery of the duodenum. The transverse colon, with its mesentery, lies free from
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| the omentum. The duodenum has a broad, fan-shaped mesentery which continues
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| cephalad to that part of the omentum forming the posterior wall of the omental
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| bursa and caudad to the common mesentery of the small intestine. The ventral
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| mesentery remains as the gastro-hepatic ligament, connecting in the usual manner
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| the lesser curvature of the stomach with the hilum of the liver.
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| The retroperitoneal sae, discovered by F. T. Lewis, has been well described by
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| Sabin, Baetjer, Heuer, and other workers in this laboratory. It is a triangular
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| structure which lies at the base of the mesentery at the level of the coeliac axis.
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| There are two small indentations along its sides, made by the adrenal bodies, which
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| thus divide the sac into two lobes. From the posterior lobe, which is the larger,
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| 6
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| LYMPHATICS IN THE STOMACH OF THE EMBRYO PIG.
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| arise the lymphatics of the intestine and of the abdominal structures, while from
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| the anterior lobe spring vessels to the stomach, spleen, duodenum, diaphragm, and
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| lungs (text-figure 2). It is this anterior portion of the sac with which we are pri-
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| marily concerned in this study. The entire sac is obliterated during development,
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| being the primordium for the chain of lymph-glands which reach from the cceliac
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| axis to the bifurcation of the aorta.
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| The gastric vessels arise by two main trunks from the anterior lobe of the retro-
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| peritoneal sac. The right trunk is much larger than the left and passes behind the
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| stomach to the lesser curvature, where it invades the stomach at three different
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| D.V.
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| TEXT-FIO. 2. Diagram of the retroperitoneal sac showing
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| ing the relation of the gastric trunks as> they leave its
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| anterior end. The early lymphatics extending to the
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| pillars of the diaphragm are also illustrated.
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| A., Adrenal; D. P., pillar of the diaphragm; D. V.,
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| diaphragmatic vessels; H. V., hepatic vessels; K., kidney;
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| R. G. T., right gastric trunk; R. P. S., retroperitoneal sac;
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| V. S. M., vessels of splenic mesentery, W. B., Wolffian
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| body.
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| points: (1) the opening of the esophagus, (2) the center of the lesser curvature, and
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| (3) the pyloric extremity of the lesser curvature. These three sets of vessels to the
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| stomach are well shown by a comparison of figures 6 and 7. It can be seen (fig. 6)
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| that another vessel of considerable size is given off from the right trunk, or arises
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| as a separate trunk from the anterior part of the retroperitoneal sac, and passes
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| through the mesentery to the duodenum (A. Duo. V.). It then extends along the
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| duodenum to the pylorus, where it anastomoses freely with the pyloric vessels,
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| reaching the stomach from its posterior surface (fig. 4) .
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| The left gastric trunk, or splenic trunk, as it may be called from its distri-
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| bution, divides into two branches. One passes directly to the cardiac pouch and
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| is not shown in the figures; the other passes through the splenic ligament to the
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| hilum of the spleen, the interior of which it has never been seen to enter, and then
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| LYMPHATICS IN THE STOMACH OF THE EMBRYO PIG. 7
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| traverses the gastro-splenic ligament to the center of the greater curvature of the
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| stomach where it ramifies to right and left (fig. 4). These lymphatics then anasto-
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| mose, over both the anterior and the posterior walls, with those from the lesser
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| curvature, where connections are formed with the lymphatics of the esophagus and
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| duodenum (cf. figures 4 and 5, plate 1).
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| After this brief description of the general pathways along which lymphatic
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| invasion of the stomach takes place, the characteristics of each invading set of
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| vessels and their part in forming the general lymphatic plexuses remain to be
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| considered.
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| jr^^^~^
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| TEXT-FIO. 3. Pig embryo,
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| 100 mm. long. Dia-
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| grammatic transverse sec-
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| tion of the stomach and
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| spleen with their perito-
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| neal ligaments. The ar-
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| rows which begin from the
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| retroperitoneal sac show
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| the directions in which
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| lymphatic invasion of the
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| stomach takes place. In
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| this specimen the stomach
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| is collapsed. The hilum
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| of the spleen is marked by
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| vessels of the splenic mes-
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| entery (V. S. M.); also
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| the greater curvature of
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| the stomach may be
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| located both by its vessels
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| (V. G. C.) cut in cross-
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| section and by the attach-
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| ment of the gastro-splenic
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| ligament.
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| The stomach may be regarded as being invaded from the posterior side at the
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| lesser curvature by the right trunk, and anteriorly along the greater curvature
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| by the left trunk. The posterior invasion of the lesser curvature takes place
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| along the gastro-hepatic ligament (the primitive ventral mesentery), while the
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| anterior invasion at the greater curvature is by way of the splenic and gastro-
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| splenic ligaments (the primitive dorsal mesentery of the stomach) and the mesentery
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| of the duodenum (text-figure 3). This arrangement offers a striking contrast to
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| the manner in which the lymphatics reach the intestine. Here, straight trunks
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| grow out from the retroperitoneal sac through the mesentery and, on reaching the
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| wall of the intestine, divide into right and left branches to surround the gut. In the
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| case of the stomach the right and left branches leave the retroperitoneal sac directly
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| and pass to the stomach by way of two separate folds of related peritoneum.
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| The earliest stage injected was an embryo 28 mm. in length (fig. 7). The
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| vessels arising from the retroperitoneal sac can be seen just reaching the stomach.
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| This is a very early stage and the injected vessels are those arising from the right
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| gastric trunk of the retroperitoneal sac. In this specimen the spleen and liver have
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| been removed. It has never been possible to inject the splenic vessels (left gastric
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| trunk) at this stage, but the mode of entrance of the right gastric trunk is well
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| illustrated. Figure 7 shows the primitive mass of lymphatics which later becomes
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| grouped into the right gastric trunk and distributed to the stomach in three parts :
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| j LI8!
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| 8 LYMPHATICS IN THE STOMACH OF THE EMBRYO PIG.
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| at the esophageal opening, at the center of the lesser curvature, and at the pylorus.
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| It is from this mass of lymphatics that most of the gastric vessels develop. It will
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| be noted in the figure that the lymphatics to the esophageal opening already suggest
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| the ring which is later to become so characteristic. The central mass to the lesser
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| curvature can be seen emerging from behind the hepatic vessels which are cut off
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| in the drawing. These vessels to the lesser curvature are shown spreading out over
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| the anterior surface of the stomach ; they also extend over the corresponding area
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| on the posterior wall. Two or three small vessels (P. V.) pass forward to the
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| pylorus and it is important to note that they always reach this structure at its
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| posterior wall. It is these vessels which will later anastomose with both the ascend-
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| ing duodenal vessels (A. Duo. V.) and the vessels of the greater curvature (V. G. C.),
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| as shown in figure 4.
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| Growth is very rapid and in slightly older specimens (35 to 45 mm.), in which
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| the splenic vessels have also appeared, the rapid invasion from the lesser cuvature is
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| apparent. The vessels reaching the esophagus have by this time formed a complete
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| subserous, periesophageal ring. This ring continues to develop and in older speci-
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| mens forms a dense, circular plexus around the esophagus, from which branches pass
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| in all directions to ramify over the stomach wall (fig. 8). The annular structure of
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| this plexus is not only manifest as a subserous set of vessels, but is maintained in
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| the depths of the stomach wall in this region as development proceeds.
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| The vessels which reach the stomach at the center of the lesser curvature are
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| by far the most numerous of any of the groups. As they traverse the gastro-
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| hepatic ligament they are in direct communication with the lymphatics of the liver,
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| which pass through this structure and also take origin from the retroperitoneal sac
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| (fig. 2) . On reaching the stomach they branch over both the anterior and posterior
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| walls and form numerous anastomoses with the vessels from the esophageal ring,
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| as well as with the lymphatics reaching the lesser curvature at the pylorus. These
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| pyloric vessels form the smallest group of lymphatics invading the stomach. They
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| spring from the right trunk just lateral to the large group at the center of the lesser
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| curvature and pass through the gastro-hepatic ligament to the posterior surface of
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| the pylorus, over which they anastomose freely with the set of vessels reaching the
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| pylorus by way of the mesentery of the duodenum.
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| This latter set of lymphatics (fig. 4), to which we may refer as the ascending
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| duodenal vessels, forms a trunk of considerable size. They can be injected only in
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| the younger embryos, due to the fact that one or more lymph glands are later | |
| formed in the mesentery of the duodenum at the pyloro-duodenal junction. Their
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| rich anastomosis with the other gastric vessels presents a subject of unusual interest,
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| inasmuch as it is not generally stated that lymphatic drainage of the stomach takes
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| place partly by way of the mesentery of the duodenum. The magnitude of early
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| vessels invading the stomach from this source and the extent of their anastomoses
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| with the gastric vessels proper give proof of a well-defined pathway by which
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| lymphatic drainage from the stomach may take place. Figures 4 and 6 show the
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| extent of the anastomosis of these ascending duodenal vessels with the other vessels
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| of the pylorus.
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| LYMPHATICS IN THE STOMACH OP THE EMBRYO PIG. 9
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| The origin of the ascending duodenal group is somewhat varied in the different
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| specimens. In some, these vessels spring from the right gastric trunk as it leaves
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| the retroperitoneal sac; in others, they arise from the sac itself just posterior to the
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| right gastric trunk. In their course through the duodenal mesentery they present
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| no unusual features, but the lymph-glands, later formed along their course at the
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| pyloro-duodenal junction, offer a striking point of difference from the glands of the
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| other vessels leaving the stomach. These glands prevent the injection of the
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| duodenal lymphatics from points on the stomach and this fact most likely accounts
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| for the failure to recognize such a connection between gastric and duodenal lym-
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| phatics by methods such as have been hitherto employed to demonstrate them.
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| The left gastric trunk, arising from the retroperitoneal sac, immediately
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| divides into two branches. The lesser branch passes by way of the extreme left
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| portion of the omental bursa to the anterior surface of the stomach at the base of
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| the cardiac pouch. The cardiac pouch is a transient, embryonic structure. In the
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| pig, during embryonic life, there is a slight annular constriction of the stomach wall
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| near the cardiac end, which gives to that portion of the stomach a pouch-like
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| appearance (fig. 5). This structure becomes less evident as development proceeds
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| and in very late stages is scarcely perceptible. The lesser branch of the left cardiac
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| trunk is the principal source of invasion of the pouch and forms rich anastomoses
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| with the vessels reaching the stomach at the center of the lesser curvature and
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| esophageal opening. The greater branch of the left gastric trunk enters the omental
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| bursa just medial to the lesser branch. It passes by way of the posterior wall of the
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| omental bursa (which in this region constitutes the splenic ligament) to the hilum of
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| the spleen; from this point these vessels pass by way of the gastro-splenic ligament
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| to the center of the greater curvature of the stomach (figs. 4 and 5). The number
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| of vessels comprising this set varies from two to four. It is always difficult to be
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| certain of the exact number, as they are situated very close together in a densely
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| entwined mass. They have never been observed to enter the spleen, and sections
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| taken through the point where they pass the hilum of that organ have consistently
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| failed to demonstrate a trace of injection mass within its interior. So it may be
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| said that these vessels appear in no way related to the spleen itself but merely take
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| advantage of its folds of peritoneum to make their way to the stomach. They
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| reach that organ on the greater curvature, at a point about midway between the
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| cardia and pylorus, and from this point their growth proceeds in opposite directions.
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| Approximately half of them pass to the right, along the greater curvature, to meet
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| the pyloric vessels from the duodenum which grow along this course ; the other half
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| pass along the greater curvature, to the left, where they meet anastomosing vessels
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| from the cardia, esophageal ring, and lesser curvature (fig. 4). All along their
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| course on the greater curvature these vessels give off branches at right angles to
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| themselves, which extend over the anterior and posterior walls of the stomach to
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| meet similar branches given off from the great mass of lymphatics of the lesser
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| curvature.
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| Concomitant with the growth of the subserous trunks, growth of the other
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| plexuses takes place. Sprouting branches from the early trunks of the subserosa
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| 10 LYMPHATICS IN THE STOMACH OF THE EMBRYO PIG.
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| dip down into the stomach wall and, as the muscular layers are traversed, the plexus
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| between the muscular layers is formed . This plexus extends throughout the stomach
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| wall, but its vessels are of smaller caliber and its meshes much less dense than those
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| of the other plexuses. It should be borne in mind, however, that vessels lying in
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| dense, muscular tissue fill less readily with injection mass than those situated in the
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| loose tissues of the submucosa and subserosa; therefore, the appearance of the
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| muscular plexus may be less dense than it really is. This point considered, the small
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| size of the vessels composing the plexus of the muscularis and their striking constancy
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| of arrangement in all well injected specimens nevertheless are facts which tend to
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| show that this plexus is a relatively scanty one.
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| On reaching the submucosa these vessels form the most extensive plexus of
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| the stomach wall, the main plexus of the submucosa. Here lymphatic growth
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| takes place very rapidly. At an early stage (20 to 40 mm.) an extremely dense
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| plexus, several layers in thickness, composed of large, tortuous vessels, has been
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| formed. In embryos 70 to 100 mm. in length the entire submucosa is found to be
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| filled by this plexus. Its presence can be easily demonstrated throughout the
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| entire stomach by injecting directly into the submucosa. As it nears the pylorus
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| its vessels become smaller and many of them appear to end blindly in this region ;
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| however, a few of them have been seen to anastomose with those of the deep plexus
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| of the duodenum. In view of the general tendency toward anastomosis exhibited
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| by the lymphatics of contiguous tissue, which is especially marked in the lymphatics
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| of the subserous plexuses of the stomach and duodenum, this scanty connection
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| between the submucosal plexuses of these two organs can scarcely be considered as
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| representing the true morphology of the lymphatics in this region. It is evident
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| that the layers of the stomach wall at the pylorus are compressed by the tone of the
| |
| pyloric musculature, as are also the lymphatic channels of the submucosa. Such a
| |
| barrier proves quite effective in preventing complete injection of the vessels of this
| |
| region. The character of the apparent endings of the vessels of the submucosa at
| |
| the pylorus favors such a view. Instead of forming a complete plexus at this
| |
| point, most of the vessels end blindly and at different points along the pylorus, thus
| |
| giving the exact picture of an incomplete lymphatic injection elsewhere in the body.
| |
| From the injections we are justified in saying only that the pathway between the
| |
| submucous plexuses of the stomach and duodenum is not easily traversable during
| |
| tonic contraction of the pylorus. A sufficient number of anastomoses between
| |
| these two plexuses has been demonstrated to show that they are connected and, by
| |
| analogy to the lymphatics of the rest of the gastro-intestinal tract, one would expect
| |
| ready communication between them during relaxation of the pyloric sphincter.
| |
| | |
| The further growth of the lymphatics in the wall of the stomach takes place
| |
| from this dense submucosal plexus. Many smaller vessels grow still farther inward
| |
| and form the scanty plexus adjacent to the muscularis mucosse. This plexus lies
| |
| at the base of the gastric glands and sends branches between them.
| |
| | |
| Figure 8, plate 3, is from a complete injection of the stomach of a pig measuring
| |
| 150 mm. It has been cut along the greater curvature and spread out to show
| |
| especially well the marked esophageal ring of lymphatics. This ring constitutes
| |
| | |
| | |
| | |
| LYMPHATICS IN THE STOMACH OF THE EMBRYO PIG. 11
| |
| | |
| one of the most striking characteristics of all injections of the stomach made before
| |
| the appearance of glands in this region. Its formation by vessels arising from the
| |
| retroperitoneal sac is well shown; branches may be observed passing in every
| |
| direction from all points of it ; those going to the cardiac pouch are well seen over
| |
| the anterior wall, while in the depths on the posterior wall are seen the vessels of
| |
| the left gastric trunk with which they anastomose. Those vessels passing to the
| |
| anterior wall are shown as a series of parallel trunks in the serosa which lead into
| |
| the deeper, much more extensive plexus of the submucosa within the depths of the
| |
| stomach wall. These serosal trunks, as well as the plexus of the submucosa, anasto-
| |
| mose with the corresponding trunks and plexus arising from the vessels of the greater
| |
| curvature ; they remind one of similar parallel trunks shown by Heuer in the develop-
| |
| ment of the lymphatics of the intestine. The posterior surface of the stomach is
| |
| seen on the left side of the figure. Here the posterior position of the pyloric vessels
| |
| arising from the lesser curvature is well shown, as is also the characteristic arrange-
| |
| ment of the serosal trunks and plexuses of the submucosa.
| |
| | |
| The development of lymphatics of the diaphragm is likewise well illustrated by
| |
| these injections. Large lymphatic trunks, accompanied by the lymphatics of the
| |
| lower lobes of the lungs which arise from this source, can be seen passing from the
| |
| anterior part of the retroperitoneal sac to the pillars of the diaphragm. The
| |
| pulmonary vessels penetrate the diaphragm, while the others spread out over its
| |
| surface. Also from the gastric plexus, at the lesser curvature of the stomach, many
| |
| large vessels pass directly to the diaphragm along the ligaments of the liver and
| |
| anastomose freely with those from the retroperitoneal sac, arriving by way of the
| |
| pillars (fig. 6) . Such an invasion of the diaphragm is readily explained by the double
| |
| origin of this structure, the pillars arising from the pleuro-peritoneal membrane,
| |
| while the body of the diaphragm arises from the ventral mesentery, septum trans-
| |
| versum, and body-wall. The embryonic lymphatics of the diaphragm are enormous
| |
| and soon cover the entire structure with a dense plexus. The active function of the
| |
| diaphragm as an agent of absorption is at once apparent by a glance at its rich
| |
| supply of lymphatics.
| |
| | |
| Here a word may be said about the lymphatics of the esophagus and their
| |
| relation to those of the stomach. Its vessels are derived from two sources. Those
| |
| of the lower end arise from the gastric vessels forming the periesophageal ring
| |
| at the cardia of the stomach, from which they spring as direct outgrowths and ex-
| |
| tend upward to a point on the esophagus about midway between the bifurcation
| |
| of the bronchi and the cardia of the stomach. Here they meet lymphatics which
| |
| have extended to the esophagus from the bronchial plexuses at the hilum of the
| |
| lungs, primarily arising from the thoracic duct. The lymphatic plexuses of the
| |
| esophagus are completed by the anastomosis of the vessels from these two sources.
| |
| In their general arrangement they are similar to those of the stomach wall, with
| |
| which they are continuous. Lymphatic drainage from the esophagus takes place
| |
| in two directions, the lower portion following the general path for gastric drainage
| |
| described for the cardia of the stomach, while the upper portion drains to the
| |
| bronchial plexuses.
| |
| | |
| | |
| | |
| 12 LYMPHATICS IN THE STOMACH OF THE EMBRYO PIG.
| |
| | |
| Information thus obtained from the injection of embryos did not necessarily
| |
| justify conclusions in regard to the lymphatic drainage in the fully developed and
| |
| adult stomach. Injections were therefore made of the stomachs of kittens, cats,
| |
| and adult pigs. In all specimens thus prepared lymphatic drainage was found
| |
| to be similar to that deduced from the study of the injected embryos. This
| |
| was clearly illustrated in the fresh stomach of a kitten 24 days old. Three
| |
| large glands were seen at the lesser curvature in the gastro-hepatic ligament, one
| |
| at the base of the splenic ligament, and one lying in the pyloro-duodenal flexure.
| |
| By injecting directly into the submucosa the paths of drainage were readily seen by
| |
| the spread of the injection mass through the lympathic plexuses of the stomach wall
| |
| and its appearance in the adjacent nodes. Injections were made at several sites:
| |
| (1) By injecting directly into the plexus of the submucosa, in the central region of
| |
| the anterior and posterior surfaces, the injection mass quickly appears in the nodes
| |
| of the lesser curvature; also, some of the vessels along the greater curvature are
| |
| filled by part of the injection flowing in that direction. Thus, the flow from the
| |
| anterior and posterior walls of the stomach was seen to pass in two principal
| |
| directions, toward the lesser and toward the greater curvatures, the major part
| |
| going to the former. (2) Injections near the pylorus and from some distance
| |
| along the adjacent greater curvature quickly flowed to the gland at the pyloro-
| |
| duodenal flexure, while, at the same time, an appreciable extent of the anterior and
| |
| posterior walls and the greater curvature was also filled. (3) When the plexus of
| |
| the submucosa near the attachment of the gastro-splenic ligament was filled, the
| |
| vessels passing from the greater curvature toward the spleen, as well as those from
| |
| the spleen to the large gland at the base of the splenic ligament, were injected.
| |
| Likewise, from this point of injection, flow occurred freely in all other directions, part
| |
| going toward the lesser curvature and part toward the pylorus.
| |
| | |
| Jamieson and Dobson made a careful study of the lymphatic drainage in the
| |
| fully developed human stomach by means of the method of injection and found the
| |
| main groups of glands to be associated with the larger arteries of the stomach and
| |
| spleen. Along the course of the coronary artery they found a group of glands
| |
| forming a periesophageal ring with another group in the gastro-hepatic ligament.
| |
| Associated with the splenic artery, in the gastro-splenic ligament, was another group
| |
| of glands. Along the course of the hepatic artery and in the bend of the duodenum,
| |
| along the gastro-duodenal artery, still other groups were observed. By injecting
| |
| directly into the submucous plexus of the stomach wall at various points, the course
| |
| of the flow of lymph to these glands was studied. From the results so obtained these
| |
| observers were led to believe that any points of division between areas drained by
| |
| any definite gland or group of glands were quite arbitrary. They found the plexus
| |
| of the muscularis to be a very scanty one. The lymphatics of all plexuses of the
| |
| stomach- wall near the cardia were seen to be continuous with those of the esophagus,
| |
| whose wall contains lymphatics arranged similarly to those of the stomach. Definite
| |
| communications were also found between both subserous and submucous plexuses
| |
| of the pyloric portion of the stomach and the duodenum. These connections of the
| |
| | |
| | |
| | |
| LYMPHATICS IN THE STOMACH OF THE EMBRYO PIG. 13
| |
| | |
| subserous plexuses were found to be rather scanty and mostly on the posterior walls
| |
| of these organs, while the submucous anastomoses were quite numerous.
| |
| | |
| Such observations are in strict accordance with the ideas one would be led to
| |
| form from a study of the development of the gastric lymphatics. The three points
| |
| of invasion from the lesser curvature correspond to the chains of glands along the
| |
| ascending and descending branches of the coronary artery and the hepatic artery.
| |
| The lymphatics reaching the stomach by way of the splenic ligaments, however,
| |
| appear to indicate that lymphatic invasion does not always take place along blood-
| |
| vessels, since the lymphatics traversing these ligaments are not accompanied by any
| |
| blood-vessels of appreciable size. More likely, it seems that related folds of perito-
| |
| neum determine the pathways by which the lymphatics reach the stomach; in many
| |
| cases the arteries take the same course. The greater number of anastomoses
| |
| between the vessels of the pylorus and duodenum than has commonly been observed,
| |
| and the fact that most of the connections between the subserous plexuses of these
| |
| organs are located on their posterior walls, are points which can be readily under-
| |
| stood from the development of the ascending duodenal group of vessels, which
| |
| are much more numerous in this region (figs. 4 and 6).
| |
| | |
| So, from the combined evidence offered by injections of developing lymphatics
| |
| in several embryonic stages, and the further injection of these vessels after the
| |
| lymphatic plexuses of the stomach have been completely formed, the lymphatic
| |
| supply of this organ is seen to be one of the richest in the entire body. Due to the
| |
| homogeneity of its plexuses, no strict division of its areas of drainage can be made
| |
| that will remain constant in any number of cases. So readily is any portion of the
| |
| stomach injected from any other part that, in all probability, the lymphatics of
| |
| the entire organ could be filled by a single injection into the submucosal plexus, if
| |
| performed slowly enough and with proper pressure. The greatest part of the
| |
| gastric drainage certainly takes place by way of the lesser curvature, but the other
| |
| two routes by way of the splenic ligaments and duodenal vessels are of quite ap-
| |
| preciable capacity. Many factors, such as peristalsis, muscle tone, venous engorge-
| |
| ment, pressure in the lymphatic vessels themselves, and (in pathological stomachs)
| |
| various degrees of obstruction must determine the relative amount of drainage by
| |
| these three outlets, the sources of whose output are in continuity and show no zonal
| |
| lines of demarcation.
| |
| | |
| | |
| | |
| 14
| |
| | |
| | |
| | |
| LYMPHATICS IN THE STOMACH OF THE EMBRYO PIG.
| |
| | |
| | |
| | |
| CONCLUSIONS.
| |
| | |
| 1. From a study of development of the lymphatics in the stomach of the embryo
| |
| pig, it is found that they invade that organ at two principal points, viz., the lesser
| |
| curvature, by way of the gastro-hepatic ligament, and the greater curvature, via
| |
| the ligaments of the spleen.
| |
| | |
| 2. Arising in common with the gastric lymphatics is a large trunk which passes
| |
| to the duodenum, then up along the duodenum to the pylorus, anastomosing
| |
| freely with the lymphatics on the posterior surface of the stomach.
| |
| | |
| 3. Part of the lymphatics invading the stomach at the lesser curvature, early
| |
| in their growth, form a dense periesophageal plexus of vessels in the subserosa.
| |
| | |
| 4. From this periesophageal ring, as well as from the other vessels reaching the
| |
| stomach at both lesser and greater curvatures, branches are given off at right
| |
| angles on both the anterior and posterior walls of the stomach. These vessels
| |
| finally meet and encircle the stomach in a segmental manner similar to that' de-
| |
| scribed by Heuer for the intestine. There are a number of connections between
| |
| these segmental subserous trunks, forming them into a subserous plexus.
| |
| | |
| 5. During the development of this plexus numerous branches from its trunks
| |
| pierce the layers of the stomach and form other gastric plexuses. All of these are
| |
| homogeneous layers of lymphatic vessels.
| |
| | |
| 6. The richness of the gastric plexuses and their numerous anastomoses preclude
| |
| the theory of any sharply defined areas whose drainage would take place in constant
| |
| given directions.
| |
| | |
| 7. There are four general pathways by which lymphatic drainage may take
| |
| place: (a) the lesser curvature, (b) the greater curvature, (c) the duodenum, and
| |
| (d) the esophagus.
| |
| | |
| I wish to thank Professor F. R. Sabin and Dr. R. S. Cunningham for the valua-
| |
| able assistance they have given me in this work, and to express my appreciation to
| |
| Mr. J. F. Didusch for the illustrations.
| |
| | |
| | |
| | |
| REFERENCES.
| |
| | |
| | |
| | |
| BAETJER, W. A., 1908. The origin of the mesenteric sac and
| |
| thoracic duct in the embryo pig. Amer. Jour. Anat.,
| |
| vol. 8.
| |
| | |
| CASH, J. R., 1917. On the development of the lymphatics in
| |
| the heart of the embryo pig. Anat. Rec., vol. 13.
| |
| | |
| , 1919. On the development of the lymphatics of the
| |
| | |
| btomach of the embryo pig. Anat. Rec., vol. 16, p. 145.
| |
| | |
| CUNEO, B., 1902. Systemelymphatique,(PoirierandCuneo).
| |
| Traite d'anatomie humaine, Poirier and Charpy.
| |
| | |
| CUNNINGHAM, R. S., 1916. On the development of the
| |
| lymphatics of the lungs in the embryo pig. Contri-
| |
| butions to Embryology, vol. 4, Carnegie Inst.
| |
| Wash. Pub. No. 224.
| |
| | |
| | |
| | |
| GRAY, H. Anatomy. Lewis ed.
| |
| | |
| HEUER, G., 1909. The development of the lymphatics in
| |
| | |
| the small intestine of the pig. Amer. Jour. Anat., | |
| | |
| vol. 9.
| |
| JAMIESON, J. R., and J. F. DOBSON, 1907. The lymphatic
| |
| | |
| system of the cjecum and appendix. Lancet.
| |
| KEIBEI, & MALL, 1912. Human Embryology.
| |
| MALL, F. P., 1896. The vessels and walls of the dog's
| |
| | |
| btomach. Johns Hopkins Hosp. Reports, vol. 1.
| |
| SABIN, F. R., 1913. The origin and development of the
| |
| | |
| lymphatic system. Johns Hopkins Hosp. Reports.
| |
| | |
| vol. 17.
| |
| | |
| | |
| | |
| ==DESCRIPTIONS OF PLATES==
| |
| | |
| | |
| PLATE 1.
| |
| | |
| Fia. 4. Pig embryo, 60 mm. Anterior view of stomach showing relation of the lymphatics of the lesser curvature to
| |
| those of the liver and diaphragm. The vessels of the splenic mesentery may be seen extending from
| |
| beneath the spleen to the greater curvature along which they have grown. Anastomosis has already
| |
| taken place between these vessels, growing toward the right along the greater curvature, and lym-
| |
| phatics from the lesser curvature, which may be seen coming from the posterior wall of the pylorus.
| |
| Anastomosis of the ascending duodenal vessels at this point is also shown. (X19.)
| |
| A. Duo. V., Ascending duodenal vessels; D., diaphragm; D. V., diaphragmatic vessels; H., liver; H. V.
| |
| hepatic vessels; S., spleen; V. G. C., vessels of the greater curvature; V. L. C., vessels of the lesser curva-
| |
| ture; V. S. M., vessels of the splenic mesentery.
| |
| | |
| FIG. 5. Pig embryo, 40 mm. Posterior view of injected stomach showing the main mass of lymphatics which reach
| |
| the stomach at the lesser curvature and their growth over the posterior stomach wall. The vessels
| |
| of the splenic mesentery are also here seen to anastomose with those extending from the lesser curvature.
| |
| These vessels, which reach the stomach by way of the gastrosplenic ligament, are also shown beginning
| |
| to extend to the right and left along the greater curvature. The spleen lies in its usual position. The
| |
| cardiac pouch is well marked in this specimen. (X 20.)
| |
| | |
| C. P., cardiac pouch; 0., esophagus; P., pylorus; S., spleen; V. G. C., vessels of the greater curvature;
| |
| V. L. C., vessels of the lesser curvature; V. S. M., vessels of the splenic mesentery.
| |
| | |
| PLATE 2.
| |
| | |
| FIG. 6. Pig embryo, 50 mm. View of stomach from right. The organ has been tilted forward to show the great mass
| |
| of lymphatics arising from the retropcritoneal sac behind it. The vessels to the duodenum and their
| |
| extension toward the stomach are shown. Lymphatics from the retroperitoneal sac, some of which
| |
| ramify over the diaphragm, others piercing it to reach the lungs, are also seen. The thoracic duct lies
| |
| at the left of the illustration. (X15.)
| |
| | |
| A. Duo. V., ascending duodenal vessels; D., diaphragm; Duo. M., mesentery of the duodenum; D. V.,
| |
| lymphatics of the diaphragm; H., liver; H. V., hepatic vessels; L., lung; Pul.. V., pulmonary
| |
| vessels, R. P. S., anterior end of retroperitoneal sac; T. D., thoracic duct; V. L. C., vessels of the lesser
| |
| curvature.
| |
| | |
| FIG. 7. Embryo pig, 30 mm. long. Anterior view of specimen from which the liver has been removed but the gastro-
| |
| hepatic ligament left intact. The dark line, along whose edges are seen cut ends of lymphatics, marks
| |
| the area from which the liver has been taken. These open vessels are those of the hepatic capsule. The
| |
| manner in which the lymphatics of the lesser curvature reach the stomach by way of the gastro-hepatic
| |
| ligament and their relations to the lymphatics of the liver are shown here. The branch of the left
| |
| gastric trunk passing to the cardiac pouch is also illustrated. The diaphragm may be seen posterior to
| |
| the cut edge of hepatic peritoneum. (X17.5.)
| |
| | |
| C. P., cardiac pouch; D., diaphragm; Duo., duodenum; D. V., diaphragmatic vessels; H. V., hepatic
| |
| vessels; L. G. T., left gastric trunk; 0., esophagus; P. V., pyloric vessels; V. L. C., vessels of the lesser
| |
| curvature.
| |
| | |
| PLATE 3.
| |
| | |
| FIG. 8. Embryo pig, 150 mm. long. Dorsal view of stomach which has been cut along its anterior surface parallel
| |
| to the greater curvature and the specimen spread out to show the relation of the lymphatics of the
| |
| lesser curvature to those of the anterior and posterior walls of the stomach. The greater curvature is
| |
| marked by the vessels which have their course along its border (V. G. C.). It may be noticed that
| |
| the superficial plexus is composed of vessels whose general course is at right angles to the curvatures,
| |
| while the deep plexus consists in a much denser, homogeneous mass of lymphatics. (X12.)
| |
| A. W., anterior wall of stomach; D. G. P., deep gastric plexus (plexus of the submucosa) ; 0., esophageal
| |
| opening; P., pylorus; Pan., pancreas; P. W., posterior wall of stomach; R.P.S., retroperitoneal sac;
| |
| S., spleen; V. G. C., vessels of the greater curvature; V. L. C., vessels of the lesser curvature.
| |