Anatomy of the vitelline vein remnant in human embryos and fetuses.

PURPOSE: To demonstrate the entire course of the human vitelline vein (VV) in specimens after degeneration of the yolk sac. METHODS: Sagittal and horizontal histological sections from 8 embryos and 19 fetuses (gestational age approximately 6-12 weeks; crown-rump length 11-61 mm) were examined. RESULTS: Two types of VV remnants were observed: a long VV on the right superior side of the mesentery of the jejunum (VV1) and a short VV on the left inferior side of the mesentery (VV2). The VV1, observed in 12 specimens, was 20-30 microns in diameter and ran dorsally between the right liver lobe and the jejunum, subsequently merging with an initial superior mesenteric vein on the pancreatic head immediately below the superior portion of the duodenum. The VV2, observed in four specimens, passed dorsally between loops of the ileum on the left side of the mesentery of the ileum and connected to the mesentery. Many of the VVs did not originate from the umbilical cord but suddenly started in the sack of physiological herniation. At 10-12 weeks, after herniation, the VVs originated from the umbilicus and were involved by the expanding greater omentum. CONCLUSIONS: The right-sided and left-sided VVs seemed to correspond to right and left VV remnants, respectively, and both took an upstream course outside the mesentery of the jejunum and ileum. The right VV upstream portion was likely to disappear later than the left one, but the timing of degeneration varied greatly among individuals, depending on the topographical relationship between the right liver lobe and the jejunum.

Anatomical Variations of Vascular Anatomy in Meckel's Diverticulum.

OBJECTIVE: The objective of the current study was to describe the anatomical variations of vessels observed in patients with Meckel's Diverticulum. METHODS: A narrative review of the literature was undertaken by means of the PubMed database, using the terms: "Meckel's Diverticulum AND vessels", "Meckel's Diverticulum AND anatomical variation" and "Meckel's Diverticulum variation". Classical anatomical textbooks were also used for normal anatomy. Additional articles provided useful information in relation to the aim of this review. Hence, the articles that met the inclusion criteria were included in this review, and the collected data were categorized into a single table. RESULTS: The majority of studies indicated the presence of an abnormal vitelline artery. Other angiographic findings concerned variations of the ileal and the iliac arteries. However, the literature revealed the presence of vascular variations without the existence of Meckel's Diverticulum, whereas a remnant of the vitelline vein may be present, but it is very rare. CONCLUSION: The detection of vascular variations accompanying Meckel's Diverticulum is not always easy and requires the correct choice of imaging method to prevent misdiagnosis.

Mechanosensitive Pathways in Heart Development: Findings from Chick Embryo Studies.

The heart is the first organ that starts to function in a developing embryo. It continues to undergo dramatic morphological changes while pumping blood to the rest of the body. Genetic regulation of heart development is partly governed by hemodynamics. Chick embryo is a major animal model that has been used extensively in cardiogenesis research. To reveal mechanosensitive pathways, a variety of surgical interferences and chemical treatments can be applied to the chick embryo to manipulate the blood flow. Such manipulations alter expressions of mechanosensitive genes which may anticipate induction of morphological changes in the developing heart. This paper aims to present different approaches for generating clinically relevant disturbed hemodynamics conditions using this embryonic chick model and to summarize identified mechanosensitive genes using the model, providing insights into embryonic origins of congenital heart defects.

Abernethy malformation draining above the diaphragm to the coronary sinus and its embryological explanations.

Abernethy malformation connecting to a supradiaphragmatic vein may be missed due to their rarity or lack of awareness. Embryological reasons explain the involvement of the left superior caval vein in these connections.

Antenatal sonographic features of persistent extrahepatic vitelline vein aneurysm confused with umbilical vein varix.

Background: The persistent vitelline vein is a portal venous system malformation arising during the embryonic period. These abnormal blood vessels frequently thrombose and can lead superior mesenteric vein obstruction or portal hypertension. Case report: We visualized a fetal intra-abdominal cystic mass with turbulent flow on prenatal ultrasound at 28 weeks' gestation. Initially diagnosed as an umbilical vein varix, it was later determined to be an extrahepatic persistent vitelline vein with an internal thrombus by postnatal ultrasound. It was successfully surgically excised. Conclusion: When an abnormal abdominal vascular structure near the umbilicus is found during prenatal ultrasonography, the persistent vitelline vein should be included in the differential diagnosis to allow prompt evaluation and treatment after birth.

Prenatal sonographic diagnosis of a vitelline vein aneurysm.

We report a case of vitelline vein aneurysm detected at 23 weeks of gestation. Few postnatal cases of vitelline vein aneurysm have been reported; however, due to their similar appearances most of them were considered initially as umbilical vein dilatations. The accurate prenatal diagnosis of vitelline vein aneurysm and early postnatal surgical treatment are crucial steps to prevent postnatal obliterative extension of thrombosis that might cause severe neonatal morbidity.

The fate of the vitelline and umbilical veins during the development of the human liver.

Differentiation of endodermal cells into hepatoblasts is well studied, but the remodeling of the vitelline and umbilical veins during liver development is less well understood. We compared human embryos between 3 and 10 weeks of development with pig and mouse embryos at comparable stages, and used Amira 3D reconstruction and Cinema 4D remodeling software for visualization. The vitelline and umbilical veins enter the systemic venous sinus on each side via a common entrance, the hepatocardiac channel. During expansion into the transverse septum at Carnegie Stage (CS)12 the liver bud develops as two dorsolateral lobes or 'wings' and a single ventromedial lobe, with the liver hilum at the intersection of these lobes. The dorsolateral lobes each engulf a vitelline vein during CS13 and the ventromedial lobe both umbilical veins during CS14, but both venous systems remain temporarily identifiable inside the liver. The dominance of the left-sided umbilical vein and the rightward repositioning of the sinuatrial junction cause de novo development of left-to-right shunts between the left umbilical vein in the liver hilum and the right hepatocardiac channel (venous duct) and the right vitelline vein (portal sinus), respectively. Once these shunts have formed, portal branches develop from the intrahepatic portions of the portal vein on the right side and the umbilical vein on the left side. The gall bladder is a reliable marker for this hepatic vascular midline. We found no evidence for large-scale fragmentation of embryonic veins as claimed by the 'vestigial' theory. Instead and in agreement with the 'lineage' theory, the vitelline and umbilical veins remained temporally identifiable inside the liver after being engulfed by hepatoblasts. In agreement with the 'hemodynamic' theory, the left-right shunts develop de novo.

Blood flow patterns underlie developmental heart defects.

Although cardiac malformations at birth are typically associated with genetic anomalies, blood flow dynamics also play a crucial role in heart formation. However, the relationship between blood flow patterns in the early embryo and later cardiovascular malformation has not been determined. We used the chicken embryo model to quantify the extent to which anomalous blood flow patterns predict cardiac defects that resemble those in humans and found that restricting either the inflow to the heart or the outflow led to reproducible abnormalities with a dose-response type relationship between blood flow stimuli and the expression of cardiac phenotypes. Constricting the outflow tract by 10-35% led predominantly to ventricular septal defects, whereas constricting by 35-60% most often led to double outlet right ventricle. Ligation of the vitelline vein caused mostly pharyngeal arch artery malformations. We show that both cardiac inflow reduction and graded outflow constriction strongly influence the development of specific and persistent abnormal cardiac structure and function. Moreover, the hemodynamic-associated cardiac defects recapitulate those caused by genetic disorders. Thus our data demonstrate the importance of investigating embryonic blood flow conditions to understand the root causes of congenital heart disease as a prerequisite to future prevention and treatment.NEW & NOTEWORTHY Congenital heart defects result from genetic anomalies, teratogen exposure, and altered blood flow during embryonic development. We show here a novel "dose-response" type relationship between the level of blood flow alteration and manifestation of specific cardiac phenotypes. We speculate that abnormal blood flow may frequently underlie congenital heart defects.

Regressing vitelline vein and the initial development of the superior mesenteric vein in human embryos.

The superior mesenteric vein was considered to develop in situ in the midgut mesentery secondary to regression of the left vitelline vein. We revisited the morphology using serial sections of 20 embryos at 5-6 weeks (CRL 9-15 mm). The regressing vitelline vein provided a long peritoneal fold in the immediately superior side of the midgut mesentery containing the thick superior mesenteric artery. Notably, in a half of specimens, there were tissue clefts along the superior mesenteric artery in the mesentery and they were communicated with the left vitelline vein at the superior end of the peritoneal fold. The tissue clefts appeared not to carry the endothelial lining. We considered the cleft as the initial superior mesenteric vein. Conversely, the initial vein seemed not to develop from budding or venous plexus.

Neonatal vitelline vein aneurysm with thrombosis: prompt treatment should be needed.

Vitelline veins are a pair of embryonic structures. The veins develop the portal vein system. Serious problems occur if the vitelline vein does not regress and becomes an aneurysm. Thrombus formation in the vitelline vein aneurysm could lead to portal vein thrombosis and portal hypertension unless promptly and correctly treated. Though vitelline vein aneurysm is an extremely rare anomaly, it rapidly progresses to portal vein thrombosis that requires prompt diagnosis and treatment. We reported a case of neonatal vitelline vein aneurysm and thrombosis that was cured by prompt operation.

An anomalous portal vein crossing the lesser sac and ending at the upper part of ductus venosus.

In serial sagittal sections of a fetus on week 9 (crown-rump length, 36 mm), we incidentally found absence of the usual portal vein through the hepatoduodenal ligament. Instead, an anomalous portal vein originated behind the pancreatic body, crossed the lesser sac and merged with the upper part of the ductus venosus. During the course across the lesser sac, the vein provided a deep notch of the liver caudate lobe (Spiegel's lobe). The hepatoduodenal ligament contained the hepatic artery, the common bile duct and, at the right posterior margin of the ligament, and a branch of the anomalous portal vein which communicated with the usual right branch of the portal vein at the hepatic hilum. The umbilical portion of the portal vein took a usual morphology and received the umbilical vein and gave off the ductus venosus. Although it seemed not to be described yet, the present anomalous portal vein was likely to be a persistent left vitelline vein. The hepatoduodenal ligament was unlikely to include the left vitelline vein in contrast to the usual concept.

Neonatal vitelline vein aneurysm with thrombosis: prompt treatment should be needed

Vitelline veins are a pair of embryonic structures. The veins develop the portal vein system. Serious problems occur if the vitelline vein does not regress and becomes an aneurysm. Thrombus formation in the vitelline vein aneurysm could lead to portal vein thrombosis and portal hypertension unless promptly and correctly treated. Though vitelline vein aneurysm is an extremely rare anomaly, it rapidly progresses to portal vein thrombosis that requires prompt diagnosis and treatment. We reported a case of neonatal vitelline vein aneurysm and thrombosis that was cured by prompt operation.

An anomalous portal vein crossing the lesser sac and ending at the upper part of ductus venosus / 대한해부학회지

In serial sagittal sections of a fetus on week 9 (crown-rump length, 36 mm), we incidentally found absence of the usual portal vein through the hepatoduodenal ligament. Instead, an anomalous portal vein originated behind the pancreatic body, crossed the lesser sac and merged with the upper part of the ductus venosus. During the course across the lesser sac, the vein provided a deep notch of the liver caudate lobe (Spiegel's lobe). The hepatoduodenal ligament contained the hepatic artery, the common bile duct and, at the right posterior margin of the ligament, and a branch of the anomalous portal vein which communicated with the usual right branch of the portal vein at the hepatic hilum. The umbilical portion of the portal vein took a usual morphology and received the umbilical vein and gave off the ductus venosus. Although it seemed not to be described yet, the present anomalous portal vein was likely to be a persistent left vitelline vein. The hepatoduodenal ligament was unlikely to include the left vitelline vein in contrast to the usual concept.

Congenital heart malformations induced by hemodynamic altering surgical interventions.

Embryonic heart formation results from a dynamic interplay between genetic and environmental factors. Blood flow during early embryonic stages plays a critical role in heart development, as interactions between flow and cardiac tissues generate biomechanical forces that modulate cardiac growth and remodeling. Normal hemodynamic conditions are essential for proper cardiac development, while altered blood flow induced by surgical manipulations in animal models result in heart defects similar to those seen in humans with congenital heart disease. This review compares the altered hemodynamics, changes in tissue properties, and cardiac defects reported after common surgical interventions that alter hemodynamics in the early chick embryo, and shows that interventions produce a wide spectrum of cardiac defects. Vitelline vein ligation and left atrial ligation decrease blood pressure and flow; and outflow tract banding increases blood pressure and flow velocities. These three surgical interventions result in many of the same cardiac defects, which indicate that the altered hemodynamics interfere with common looping, septation and valve formation processes that occur after intervention and that shape the four-chambered heart. While many similar defects develop after the interventions, the varying degrees of hemodynamic load alteration among the three interventions also result in varying incidence and severity of cardiac defects, indicating that the hemodynamic modulation of cardiac developmental processes is strongly dependent on hemodynamic load.

Extrahepatic vitelline vein aneurysm: prenatal diagnosis and follow up.

Umbilical vein varix is a well-described prenatal anomaly in which the prognosis remains unclear. We describe a very rare venous malformation that mimicked an umbilical vein varix consisting of a persistent vitelline vein. From 2003 to 2010, three patients were referred starting at 20 weeks gestation to our prenatal centers for an umbilical vein varix diagnosis. Fetal follow up was unremarkable, with the exception of the dilated vein size (mean: 35 mm at 33 weeks gestation). After birth, the three children presented with thrombosis from the aneurysmal sac to the portal trunk. All the children underwent surgical thrombectomy and resection of the aneurysmal sac after birth. Operative findings showed no umbilical vein but an abnormal dilated and thrombosed vein coming from the umbilicus to the portal vein following the right vitelline vein trajectory. One child was treated with systemic heparin. Median follow up is 5.6 years. Currently, one patient has a normal portal flow. The other two have persistent portal vein thrombosis with portal cavernoma and portal hypertension. This malformation is rare and should be considered in cases of early diagnosed umbilical vein varix whose diameter is greater than 20mm. We advocate an early surgical thrombectomy with heparinization to prevent portal vein thrombosis.

Abnormal continuation of umbilical vein into extra-hepatic portal vein: Report of three cases.

Anomalies of the umbilical venous system are perplexing essentially due to dissection errors and vascular connection delineation failure. Continuation of umbilical vein into the extra-hepatic portal vein is classified as group IV umbilical vein anomaly and involves the vitelline vein or its remnants. Despite this categorization most examiners ascribe fetal extra hepatic abdominal vascular abnormality as an umbilical vein anomaly. Since these anomalies involve vitelline vein, the term "umbilical vein anomaly" is inappropriate and should be referred to as "vitelline vein abnormalities". Vitelline vein abnormalities are exceedingly rare and to the best of our knowledge only three cases have been reported prenatally. We report three cases presenting with intrauterine fetal demise and on perinatal autopsy demonstrating aneurysmally dilated group IV umbilical vein anomaly. Review of the literature, embryological basis and clinical implications of persistent vitelline vein and its varix are discussed.

A Clinical Study of Vitelline Duct and Vessel Remnants

Of 72 cases with vitelline duct and vessel remnants, 45 (62.5%) had symptomatic lesions (mean age, 27.9 months) with male preponderance (4.6: 1). Among the 45 symptomatic lesions, there were 22 cases of Meckel's diverticulum, 6 cases of Meckel's diverticulum with fibrous band attached to the umbilicus, 6 cases of patent vitelline duct, 5 cases of vitelline artery remnant as fibrous band, 2 cases of umbilical sinus, 2 cases of umbilical polyp, and 2 cases of vitelline cyst. Twenty three cases (51%) presented with intestinal obstruction, 6 (13%) with rectal bleeding, 4 (9%) with perforated Meckel's diverticulum, 5 with intestinal fluid drainage through umbilicus, 5 with umbilical lesion, and 1 with abdominal mass. Intestinal obstruction due to fibrous band developed at infancy (average age, 4.6 months). About 82% of complicated Meckel's diverticulum (n=28) presented less than 4 years of age. Seventeen Meckel's diverticulums, 8 obliterated vitelline artery remnants, and 1 vitelline vein remnant as fibrous band were found incidentally at laparotomy.