Partial depletion of neuropeptide Y from noradrenergic perivascular and cardiac axons by 6-hydroxydopamine and reserpine

The effects of 6-hydroxydopamine (6-OHDA) and reserpine on the storage of neuropeptide Y (NPY) in noradrenergic cardiovascular nerves were examined with both immunohistochemistry and radioimmunoassay (RIA). Immunohistochemical double-labelling techniques demonstrated that NPY was located only in noradrenergic axons in the guinea-pig carotid artery, mitral valve, thoracic inferior vena cava, thoracic aorta, superior mesenteric artery and small saphenous vein. Treatment with 6-OHDA in vivo eliminated noradrenergic, NPY-containing axon terminals from all tissues, but preterminal axons were still prominent in the superior mesenteric artery. The greatest depletion of NPY detected by RIA after 6-OHDA treatment was found in tissues with a predominance of terminal noradrenergic axons, such as the small saphenous vein, whereas NPY accumulating in preterminal axons masked the loss of NPY from terminal axons in the superior mesenteric artery. After treatment with doses of reserpine that led to a rapid depletion of noradrenaline (NA) from perivascular nerves, NPY was still detected histochemically at all times although levels sometimes appeared to be reduced. RIA demonstrated that the partial depletion of NPY after reserpine consisted of a rapid phase seen in the vena cava and saphenous vein after the highest doses, and a slower phase of NPY depletion from all tissues after all doses of reserpine. The greatest depletion of NPY from terminal axons by reserpine (in small saphenous vein) was 85-90%. These results demonstrate that some NPY can be stored in noradrenergic perivascular axons in the absence of noradrenaline, but that partial depletion of NPY from axon terminals results when NA stores are depleted by reserpine. The variation in extent of NPY depletion between tissues after drug treatments can be explained by variation in the ratio of preterminal to terminal axons.     

Anlage of the initial part of the thoracic duct in human embryogenesis]

Canalization of the jugular lymphatic sac is accompanied with disengagement from the blood stream of the thoracic subcardinal and the thoracic parts of the superior mesocardinal veins, forming the paired thoracic anlage of the thoracic duct (ThD). Canalization of the retroperitoneal lymphatic sac (RLS) is combined with differentiation of the antevertebral plexus of the abdominal veins, formation of the ThD cistern. Lateroaortal, retrocaval and retroaortal lumbar trunks (LT) become its roots. Together with RLS and the ThD cistern they form the lymphatic "muff" around the abdominal aorta and inferior vena cava. The degree of its parts separation and its substitution by collaterals of LT and by lymph nodes determines the variants of the definitive organization of the ThD initial part. Already at the stage of anlage the intestinal trunk is not included in the ThD root system, but serves as the RLS anterior tributary, or its lumbar, preaortic tributary.     

The zero-stress state of rat veins and vena cava

The zero-stress state of a vein is, like that of an artery, not a closed cylindrical tube, but is a series of segments whose cross-sections are open sectors. An opening angle of each sector is defined as the angle subtended between two radii joining the midpoint of the inner wall to the tips of the inner wall. Data on the opening angles (mean +/- standard deviation) of the veins and vena cava of the rat are presented. For the superior vena cava and subclavian, jugular, facial, renal, common iliac, saphenous, and plantar veins, the opening angle varies in the range of 25 to 75 deg. The inferior vena cava (below the heart), however, has noncircular, nonaxisymmetric cross-sections, a curved axis, and a rapid longitudinal variation of its "diameter"; its zero-stress state is not circular sectors; but the opening angle is still a useful characterization. The mean opening angle of the interior vena cava varies in the range of 40 to 150 deg in the thoracic portion, and 75 to 130 deg in the abdominal portion, with the larger values occurring about the middle of each portion. There are considerable length, diameter reductions, and wall thickening of the vena cava from the homeostatic state to the no-load state in vitro. Physically, the zero-stress state is the basis of the stress analysis of blood vessels. The change of opening angle is a convenient parameter to characterize any nonuniform remodeling of the vessel wall due to changes in physical stress or chemical environment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hemodynamics mechanisms of changes in the right atrial pressure following intravenous injection of the depressor drugs

Changes of the right atrial pressure, superior and inferior vena cava flows, right ventricular myocardial contractility (first derivate of right ventricular pressure, dP/dt max) following i.v. injection of acetylcholine, histamine and isoproterenol, were studied in acute experiments on anaesthetized mongrel cats with artificial lung ventilation and opened chest. The right atrial pressure in those cases could be increased (I group of animals) or decreased (II group). In maximal shifts of right atrial pressure following acetylcholine injection, the superior vena cava flow increased but the inferior vena cava flow decreased in equal proportion. When the right ventricular myocardial contractility decreased more than the right atrial pressure was augmented, and when the cardiac negative inotropic effect was weak, the right atrial pressure was reduced. After histamine injection in both groups of animals, right ventricular myocardial contractility was increased on the same level, and changes of the inferior vena cava flow were insignificant. The right atrial pressure was elevated following greater increase of superior vena cava flow. Isoproterenol caused the positive cardiac inotropic effect and augmenting of the superior vena cava flow in both groups of animals. The right atrial pressure was elevated if the inferior vena cava flow increased and, on the other hand, when the inferior vena cava flow decreased the right atrial pressure was reduced. Thus different maximal changes of the right atrial pressure following i.v. injection of acetylcholine, histamine and isoproterenol could be explained by different hemodynamic mechanisms of the interaction between superior and inferior vena cava flow shifts and changes of the right ventricular myocardial contractility.     

Schistosoma mansoni: mechanism of attrition and routes of migration from lungs to hepatic portal system in the laboratory mouse

The number of schistosomula in the axillary lymph nodes of mice was determined by compressed tissue autoradiography at 13 intervals from 0.5 to 28 days after exposure of abdominal skin to 75Se-labeled cercariae of S. mansoni. Significant accumulations were observed between days 3 and 6 and peaked on day 4 at which time 9.4 +/- 1.1% of the schistosomula present in the whole body were found in the axillary lymph nodes. The total number and distribution of schistosomula in all tissues of mice were likewise determined at 12 intervals from 3 to 24 days following exposure. The frequent appearance of small numbers of schistosomula in trachea and esophagus suggested that normal attrition resulted at least in part from physical expulsion of schistosomula from the body by way of the tracheobronchial tree and gastrointestinal tract. The distribution of schistosomula observed in heart chambers, caudal vena cava, hepatic portal vein, aorta, intestinal wall, thoracic cavity rinses, and diaphragm supported all 3 standing hypotheses regarding route of migration from lungs to hepatic portal system, i.e., that schistosomula migrate via (1) the pulmonary artery, right heart, caudal vena cava, and hepatic veins, (2) the pulmonary vein, left heart, aorta, and cranial mesenteric artery, and (3) the thoracic cavity and diaphragm.     

Accumulation of calcium and phosphorus accompanied by inevitable accumulation of magnesium in human arteries

To examine whether there were differences between races in regard to the relationships among element contents in the arteries, the authors investigated the relationships among the average contents of calcium, phosphorus, sulfur, and magnesium in the 18 kinds of the Thai artery. After ordinary dissection by medical students at Chiang Mai University was finished, the thoracic and abdominal aortas, ramifying site of the abdominal aorta into the common iliac arteries, coronary, common carotid, internal thoracic, subclavian, axillary, brachial, radial, superior and inferior mesenteric, renal, common iliac, internal iliac, and external iliac arteries were resected from the subjects who consisted of 12 men and 3 women, ranging in age from 39 to 84 yr. The femoral and posterior tibial arteries were resected from the subjects, consisting of 15 men and 5 women, ranging in age from 25 to 88 yr. The element content of the arteries was analyzed by inductively coupled plasma-atomic emission spectrometry. It was found that there were extremely significant direct correlations among the average contents of calcium, phosphorus, and magnesium in the 18 kinds of the Thai artery, but no significant correlations were found between the average contents of sulfur and elements, such as calcium, phosphorus, and magnesium. These results were in agreement with those of the Japanese arteries. Therefore, it was suggested that there was no significant difference between the arteries of the Thai and the Japanese in the relationships among calcium, phosphorus, sulfur, and magnesium.     

The vascular territories of the superior epigastric and the deep inferior epigastric systems

The vascular territories of the superior and the deep inferior epigastric arteries were investigated by dye injection, dissection, and barium radiographic studies. By these means it was established that the deep inferior epigastric artery was more significant than the superior epigastric artery in supplying the skin of the anterior abdominal wall. Segmental branches of the deep epigastric system pass upward and outward into the neurovascular plane of the lateral abdominal wall, where they anastomose with the terminal branches of the lower six intercostal arteries and the ascending branch of the deep circumflex iliac artery. The anastomoses consist of multiple narrow "choke" vessels. Similar connections are seen between the superior and the deep inferior epigastric arteries within the rectus abdominis muscle well above the level of the umbilicus. Many perforating arteries emerge through the anterior rectus sheath, but the highest concentration of major perforators is in the paraumbilical area. These vessels are terminal branches of the deep inferior epigastric artery. They feed into a subcutaneous vascular network that radiates from the umbilicus like the spokes of a wheel. Once again, choke connections exist with adjacent territories: inferiorly with the superficial inferior epigastric artery, inferolaterally with the superficial circumflex iliac artery, and superiorly with the superficial superior epigastric artery. The dominant connections, however, are superolaterally with the lateral cutaneous branches of the intercostal arteries. For breast reconstruction, it would appear that prior ligation of the deep inferior epigastric artery would be of advantage when elevating the lower abdominal skin on a superiorly based rectus abdominis musculocutaneous flap. The vascularity of this flap would be further increased by positioning some part of the skin paddle over the dense pack of large paraumbilical perforators. Based on these anatomic studies, the relative merits of the superior and deep inferior epigastric arteries with respect to local and distant tissue transfer using various elements of the abdominal wall are discussed in detail.     

Heterotopic heart transplantation in mice

The mouse heterotopic heart transplantation has been used widely since it was introduced by Drs. Corry and Russell in 1973. It is particularly valuable for studying rejection and immune response now that newer transgenic and gene knockout mice are available, and a large number of immunologic reagents have been developed. The heart transplant model is less stringent than the skin transplant models, although technically more challenging. We have developed a modified technique and have completed over 1000 successful cases of heterotopic heart transplantation in mice. When making anastomosis of the ascending aorta and abdominal aorta, two stay sutures are placed at the proximal and distal apexes of recipient abdominal aorta with the donor s ascending aorta, then using 11-0 suture for anastomosis on both side of aorta with continuing sutures. The stay sutures make the anastomosis easier and 11-0 is an ideal suture size to avoid bleeding and thrombosis.When making anastomosis of pulmonary artery and inferior vena cava, two stay sutures are made at the proximal apex and distal apex of the recipient s inferior vena cava with the donor s pulmonary artery. The left wall of the inferior vena cava and donor s pulmonary artery is closed with continuing sutures in the inside of the inferior vena cava after, one knot with the proximal apex stay suture the right wall of the inferior vena cava and the donor s pulmonary artery are closed with continuing sutures outside the inferior vena cave with 10-0 sutures. This method is easier to perform because anastomosis is made just on the one side of the inferior vena cava and 10-0 sutures is the right size to avoid bleeding and thrombosis. In this article, we provide details of the technique to supplement the video.     

Various forms of the celiac trunk and its anastomoses with the superior mesenteric artery]

Three rare varieties of upper abdominal arteries were compared with similar cases in the anatomical literature. An attempt was made to obtain a classification of the supernumerary branches of the celiac trunk and of the anastomoses between the celiac trunk and the superior mesenteric artery. One or more supernumerary branches of the celiac artery can be observed: (1) the superior mesenteric artery; (2) an accessory hepatic artery; (3) a posterior pancreatic artery; (4) a colic artery; (5) an accessory splenic artery; (6) a connecting branch to the superior mesenteric artery, and (7) an inferior phrenic artery. The following types of anastomoses between the celiac artery and the superior mesenteric artery can be distinguished: (1) direct connection; (2) anastomoses within the hepatic artery; (3) anatomoses following pre- or postnatal stenosis, and (4) the pancreatic arcades. For the first type the theory of TANDLER (longitudinal anastomosis) is abandoned. The development of the second type is as yet unresolved. In the case of the last two types a postembryonal formation is possible.     

Distribution of the vasoconstrictor and vasorelaxant effects of norbormide along the vascular tree of the rat

Norbormide is a vasoconstrictor of rat peripheral arteries and a relaxant in rat aorta. To characterise norbormide actions within the rat vascular tree we have investigated its effects on the contractile function of rings from several arteries and veins. A maximal norbormide concentration (50 microM) failed to contract thoracic aorta and carotid artery, whereas in pulmonary artery, abdominal aorta, iliac, caudal, and femoral arteries it induced a contractile effect that was respectively 4.8 +/- 0.6, 18.4 +/- 1.5, 39 +/- 5, 144 +/- 7, and 260 +/- 22% of that induced by 90 mM KCl. In pulmonary, carotid, and iliac arteries, and in thoracic and abdominal aorta, 50 microM norbormide inhibited KCl-induced responses. Norbormide (50 microM) contracted all veins investigated. The effect, expressed as % of KCl-induced contraction, was 121 +/- 25, 154 +/- 14.5, 154 +/- 18.2, 203 +/- 19, and 267 +/- 33 for pulmonary vein, thoracic and abdominal vena cava, iliac and jugular veins, respectively. In jugular vein, as previously shown in rat caudal artery, norbormide contraction was abolished in Ca2+-free medium, was unaffected by the Ca2+ channel blocker nifedipine, and was relaxed by SK&F 96365, a blocker of store-operated Ca2+ channels. In conclusion: i) rat veins represent the main target for contractile norbormide action; ii) in both artery and veins norbormide contractions are generally inversely related to the calibre of the vessel; iii) norbormide-induced contraction is mediated by the same mechanism/s in arteries and veins; iiii) in norbormide-contracted arteries the drug activates both contractile and relaxing mechanisms.     

Ultrasound studies in varicocele

Renal function, the anatomic and functional status of the vena cava inferior, renal arteries and veins, and spermatic veins were evaluated in healthy individuals and patients with varicocele before and 12 months after laparoscopic ligation of the left spermatic vein. The renal vessels were assessed by color Doppler ultrasonography and renal function was examined by complex radionuclide study with 99mTc-pentatech. There were no significant changes in the diameter of renal arteries and vena cava inferior and the right arterial blood flow velocities in healthy individuals and patients. No difference were found in the diameter of renal veins and in the blood flow velocity in renal arteries and veins. The enlarged renal veins and decreased mean blood flow velocity in the left renal vein in healthy persons and patients with varicocele and lower blood flow in the left renal artery than in the right one indicate left-sided renal hypertension that is attributable to left renal vein overload due to a great variety of collaterals and to compression at the site of "a forcepts". At the same time 12-month postoperative ultrasonic, Doppler and complex radionuclide studies revealed no significant changes in the diameter and blood flow velocity in the left renal vein.     

Accumulation of elements in the arteries and cardiac valves of Thai with aging

To elucidate whether the extent of element accumulation in the arteries and cardiac valves with aging was different between different races, the authors investigated the accumulation of elements in the arteries and cardiac valves of the Thai with aging and the relationships among elements in the cardiac valves. After ordinary dissection at Chiang Mai University was finished, 16 arteries and 4 cardiac valves were resected and element contents were determined by inductively coupled plasma-atomic emission spectrometry. In the 16 arteries, the average content of calcium was the highest in the site of the abdominal aorta ramifying into the common iliac arteries, and it decreased in the order internal iliac, coronary, abdominal aorta, common iliac, external iliac, superior mesenteric, inferior mesenteric, thoracic aorta, brachial, radial, common carotid, subclavian, ulnar, axillary, renal, and internal thoracic arteries. The average contents of phosphorus and magnesium in respective arteries were parallel with the average contents of calcium, except for the coronary artery. In comparison with the arteries of the Japanese, the trend of calcium accumulation in the arteries of the Thai was almost similar to that in the arteries of the Japanese, except for the coronary artery and thoracic aorta. The calcium accumulation in the coronary artery was much higher in the Thai than in the Japanese, whereas that in the thoracic aorta was lower in the Thai than in the Japanese. Regarding elements in the cardiac valves, the calcium content increased remarkably in the seventies in the aortic valve and in the nineties in the pulmonary valve, but it hardly increased in both the mitral and tricuspid valves with aging. The average content of calcium was the highest in the aortic valve, and it decreased in the order pulmonary, tricuspid, and mitral valves. Regarding the relationship among elements in the aortic valves, it was found that there were extremely significant direct correlations among the contents of calcium, phosphorus, and magnesium, whereas there were significant direct correlations between zinc and either calcium or phosphorus contents. Although significant correlations were found between sulfur and the other element contents in the aortic valves of the Japanese, no significant correlations were found between them in the aortic valves of the Thai. In the mitral valves, extremely or very significant direct correlations were found among the contents of calcium, phosphorus, magnesium, and sulfur, with some exceptions that there were no significant correlations between phosphorus and either magnesium or sulfur contents. In addition, no significant correlation was found in the calcium content between the aortic valve and coronary artery in the same individuals.     

Topographic anatomical interrelation of the lumbar triangles with the organs and adipose tissue formations of the retroperitoneal space

The investigation has been carried out in 96 corpses of fetuses, newborns and mature persons by means of preparation methods, injection of fatty formations of the retroperitoneal space, superior urinary pathways and vessels with x-ray contrast masses and subsequent roentgenography. The area of the lumbar triangles is subjected to certain fluctuations and only in some cases they are absent. The kidneys, peritoneal part of the ureters, duodenum, pancreas, aorta and inferior vena cava in the projection of the lumbar triangles are not situated. The lumbar triangle can be used for performing drainage, when the organs and formations of the retroperitoneal space are operated on.     

Renal extraction of circulating adiponectin in patients with renovascular hypertension

BACKGROUND: Patients with chronic renal failure are characterized by an elevated plasma adiponectin concentration, which is significantly lowered after successful kidney transplantation. The direct renal clearance and extraction of adiponectin have not yet been documented in humans. Therefore the aim of the study was to estimate separate kidney extraction of adiponectin, by measuring its concentration in the aorta and both renal veins, in patients with renovascular hypertension caused by unilateral renal artery stenosis. METHODS: In 30 patients with significant (> 70%) unilateral renal artery stenosis, plasma adiponectin was measured in blood samples taken from the aorta, both renal veins and the vena cava inferior below the orifices of the renal veins. RESULTS: Renal venous plasma adiponectin concentrations (both from the kidney with renal artery stenosis and from the contralateral organ) were only numerically lower than the concentrations measured in the aorta (11.10 [8.65-13.56]; 11.12 [8.81-13.42]; 11.35 [8.90-13.80] microg/ml, respectively). Fractional extraction of adiponectin was 5.0 [-1.6-11.0]% in the kidney with renal artery stenosis and 3.0 [-2.4-9.01% in the contralateral "normal" kidney. Slightly higher concentrations of plasma adiponectin were observed in the vena cava inferior below the orifices of the renal veins (11.79 [9.14-14.44] microg/ml). In patients with unilateral renal artery stenosis significant negative correlations were found between plasma adiponectin concentration obtained from the vena cava inferior below the orifices of renal veins and eGFR (r = -0.38; p < 0.05), systolic (r = -0.71; p < 0.0001) and diastolic blood pressure (r = -0.40; p < 0.04), as well as serum triglyceride concentrations (r = -0.64; p < 0.001). CONCLUSION: The findings indicate that the fractional renal extraction of adiponectin is rather low.     

Intravascular pressure profiles in elephant seals: hypotheses on the caval sphincter, extradural vein and venous return to the heart

In order to evaluate hemodynamics in the complex vascular system of phocid seals, intravascular pressure profiles were measured during periods of rest-associated apnea in young elephant seals (Mirounga angustirostris). There were no significant differences between apneic and eupneic mean arterial pressures. During apnea, venous pressure profiles (pulmonary artery, thoracic portion of the vena cava (thoracic vena cava), extradural vein, and hepatic sinus) demonstrated only minor, transient fluctuations. During eupnea, all venous pressure profiles were dominated by respiratory fluctuations. During inspiration, pressures in the thoracic vena cava and extradural vein decreased -9 to -21 mm Hg, and -9 to -17 mm Hg, respectively. In contrast, hepatic sinus pressure increased 2-6 mm Hg during inspiration. Nearly constant hepatic sinus and intrathoracic vascular pressure profiles during the breath-hold period are consistent with incomplete constriction of the caval sphincter during these rest-associated apneas. During eupnea, negative inspiratory intravascular pressures in the chest ("the respiratory pump") should augment venous return via both the venae cavae and the extradural vein. It is hypothesized that, in addition to the venae cavae, the prominent para-caval venous system of phocid seals (i.e., the extradural vein) is necessary to allow adequate venous return for maintenance of high cardiac outputs and blood pressure during eupnea.     

Adrenocortical Carcinoma Invading the Inferior Vena Cava: Case Report And Literature Review

ObjectiveTo present the case of a man with a rightsided adrenocortical carcinoma that invaded the inferior vena cava and was managed by radical resection and vein patch repair.MethodsWe report the clinical, laboratory, imaging, and operative findings, and we highlight the pertinent features of this case. The literature is reviewed for the management of adrenocortical carcinoma in conjunction with inferior vena cava invasion.ResultsIn a 34-year-old man with new-onset abdominal pain, abdominal imaging disclosed a large right adrenal mass with invasion into the inferior vena cava. Laboratory values revealed that the adrenal mass was likely nonfunctional. At surgical intervention with use of cardiopulmonary bypass, the mass was removed en bloc with the adrenal gland, right kidney, and the wall of the inferior vena cava, and the inferior vena cava was reconstructed with bovine pericardium.ConclusionDespite direct invasion or extension of tumor thrombus into the inferior vena cava (or both), complete (R0) resection can be obtained. Thus, this scenario should not preclude attempted curative resection in patients with adrenal cancer. (Endocr Pract. 2008;14: 721-725)     

大鼠肾移植慢性排斥反应模型的建立

目的建立稳定而可靠的大鼠肾移植慢性排斥反应模型。方法选用30只Wistar大鼠为供体,30只SD大鼠为受体。取供体左肾,采用HC-A离体肾保存液原位灌注,将供肾动、静脉分别与受体腹主动脉、下腔静脉行端侧吻合,以输尿管膀胱植入法行尿路重建,建立大鼠同种异体肾移植模型。分别于术后3、6、9周取移植肾观察大体和组织形态学变化,观察术后并发症及排斥反应情况。结果移植肾脏大体和组织形态学呈渐进性变化,至术后9周可出现明显的慢性排斥反应病理改变。移植肾脏可顺利存活,部分出现肾积水并发症,但不影响排斥反应病理变化。结论本方法可建立稳定、可靠的肾移植慢性排斥反应模型,是研究慢性排斥反应的理想模型。     

Ostium of the collection stem of the anterior cardiac veins (vv. cardiacae anteriores) in the vena cava, inferior

In 1 of 150 studied cases, we found the collection stem of anterior cardiac veins that emptied into the inferior vena cava. This collection stem had eight tributaries: two right atrial veins, five anterior cardiac veins and a right marginal vein. The caliber of the collection stem was increasing gradually from its beginning (2.8 mm) to its orifice (4.5 mm). The orifice of the collection stem was in the inferior vena cava, at a distance of 10 mm from its ostial valve, and was itself provided with a semilunar valve.     

Distensibility characteristics of caval veins and empirical exponential formulae

The stress-strain curves of the vena cava have been measured of vena cava superior, and the intrathoracic and abdominal portions of vena cava inferior excised from dogs. The stress sigma is expressed by the exponential function of the strain gamma as follows: sigma = sigma 0[exp (gamma/gamma 0) - 1] in the longitudinal direction, and sigma = sigma 1[exp(gamma/gamma 1) - 1] + sigma 2 [exp(gamma/gamma 2) - 1] in the circumferential one for all the three kinds of veins. The constants sigma 0, gamma 0, sigma 1, gamma 1, sigma 2 and gamma 2 are determined by a nonlinear least squares method.     

The early development of the lymphatic system in mouse embryos.

The early development of the lymphatic system was studied in embryos of an inbred strain of the laboratory mouse. During the first stage of its development the system is represented by a more or less regular series of small and blind-ending outgrowths of the major embryonic veins which develop in a cranio-caudalward direction from the jugular to the pelvic region. As a result of differences in growth rates of adjacent anatomical structures this series of early lymphatic primordia becomes subdivided into 4 singular primordia and 12 groups of primordia. After the constituents of each group of early primordia have fused, 16 isolated lymphatic plexuses (sacs) are formed of which 14 are in bilaterally symmetric and 2 are in a median line position: i.e. bilaterally: (1) the jugulo-axillary lymph sac situated lateral to the anterior cardinal vein and dorsal to the primitive ulnar vein and its major branch, the external mammary vein, (2) the paratracheal lymph plexus situated medial to the anterior cardinal vein, (3) the internal thoracic lymph plexus situated lateral to the thoracic part of the posterior cardinal vein, (4) the thoracic ducts situated medial to the thoracic part of the posterior cardinal vein, (5) the lumbar lymph plexus situated dorso-lateral to the abdominal part of the posterior cardinal vein, (6) the subcardinal lymph plexus and (7) the iliac lymph plexus situated ventro-lateral to the abdominal part of the posterior cardinal vein; and in the median line: (8) the subtracheal lymph plexus situated at the confluence of the pulmonary veins and (9) the mesenteric lymph plexus situated near the confluence of the splenic and the superior mesenteric veins. Except for some openings at the jugulo-subclavian confluence all connections with the veins disappear. From the primordia extensions grow out centrifugally. They invade the surrounding tissues and, in part, fuse with similar sprouts of adjacent primordia. In this way a continuous system of lymph truncs is formed that opens into the venous system at the jugulo-subclavian confluence.