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PubMed1999

Anomalies of the inferior vena cava and renal veins: embryologic and surgical considerations.

Anomalies of the inferior vena cava and renal veins occur infrequently but if unidentified can lead to significant morbidity during surgical exploration. An understanding of the embryologic development of the vena cava and its tributaries is necessary to understand the genesis of these sometimes complex anomalies and their accompanying anatomic variants. Newer radiologic modalities in the form of spiral computed tomography (CT) and three-dimensional reconstruction of spiral CT allow clear definition of the anatomy of these anomalies. Variations in the embryologic evolution of the vena cava dictate the different venous anomalies that may be encountered in the retroperitoneum. Additionally, the utility of newer radiologic modalities in the identification of these anomalies is discussed.

Humans↗

PubMed2001

Systemic venous abnormalities: embryologic and echocardiographic considerations.

The echocardiographic diagnosis of systemic venous anomalies often is rendered difficult by the variety of lesions that exist. An understanding of the embryologic processes that result in these lesions is essential for accurate identification, since these lesions often are not obvious on routine echocardiographic examination. Standard echocardiographic views may demonstrate some lesions, whereas many require modified views to outline the abnormal systemic venous anatomy. This paper reviews the basic embryologic processes of the development of the normal and abnormal systemic venous system, as well as the echocardiographic identification of these major systemic venous malformations.

Cardiovascular Abnormalities↗

PubMed2003

The embryology of gut rotation.

Until today, the puzzling spectrum of midgut "malrotations" is commonly explained by an "impaired" process of rotation of the midgut. However, a closer look at the literature reveals that the description of this "process of rotation" is rather schematic and is aimed more at explaining pathological findings, while detailed proper embryological investigations are still rare. Despite recent trials, good animals models that would allow the comparison of normal and abnormal midgut development are still missing. In the first part of this article, the "normal process of rotation," as it is described in the literature, is presented and critically analyzed. In general, it is a shortcoming that reliable illustrations of these crucial embryological processes are missing in most of these papers. Therefore, in the second part of this review scanning electron microscopy pictures of the developing midgut are presented in a series of rat embryos. In these pictures clear signs of a process of rotation are missing.

Animals↗

PubMed2002

Magnetic resonance imaging in children with anorectal malformations: embryologic implications.

PURPOSE: The aim of this study was to evaluate the spectrum of developmental anomalies in the caudal region of patients with anorectal malformations (ARM) and relate them to the new insights in the embryogenesis of this region. METHODS: Forty-nine patients with ARM were investigated with magnetic resonance imaging (MRI); 24 preoperatively (preop) and 25 postoperatively (postop). Of this group, 17 patients had a high (or intermediate) ARM, 28 a low ARM, and 4 a cloacal malformation (CM). The evaluation of the imaging studies included the level and type of ARM (preop); the developmental state of the sphincter muscle complex (SMC); and the associated anomalies of spinal cord, spine, and urogenital system. The anomalies detected were ordered and related to recent embryologic observations in the caudal region. RESULTS: With MRI, the level of ARM was depicted effectively in 23 of 24 patients (96%) investigated preop, including 5 of 9 clinically proven fistulae in those with high ARM and CM (56%). Maldevelopment of the SMC was observed in 14 of 49 patients (29%). Associated anomalies of spinal cord and spine were found in 51% of patients, more frequently in those with high ARM, low ARM with fistulae, and cloacal malformations. Associated anomalies of the urogenital system were found in 37% of patients. CONCLUSIONS: As illustrated by the current study, MRI has become indispensable for the visualization of the nature of congenital ARM and associated anomalies. Moreover, MRI aids in understanding the morphology and pathogenesis of these complex congenital malformations. Based on the MRI and recent embryologic observations, a new and simplified classification of ARM is introduced, including a more appropriate nomenclature.

Abnormalities, Multiple↗

PubMed2003

The embryology of the foregut.

Until today, several theories have been developed to explain the occurrence of common foregut malformations as esophageal atresia and tracheoseophageal fistula. Most researchers believe that these malformations are the result of an impaired process of septation of the early foregut. However, a detailed review of the literature makes clear that a unified embryologic concept of the normal foregut development is still missing. This statement is still true after the development of an animal model, the so-called Adriamycin model in rats, which allows the reproduction of embryos, fetuses, and newborns with a huge spectrum of malformations, including foregut malformations. In the first part of this review, data from the literature are presented and analyzed critically, which deal with the differentiation of the foregut into the esophagus and the respiratory tract. In general, it is a shortcoming that reliable illustrations of these crucial embryologic processes still are missing in most of these reports. Therefore, in the second part, scanning electron microscopy pictures of the developing foregut are presented in a series of chicken embryos. In these pictures, signs of a septum are completely missing as an important structure during the differentiation of the foregut. In the third part, the spectrum of theories that should explain abnormal foregut malformations is presented and critically discussed. In the last section, the Adriamycin model and its implications for the current understanding of the foregut malformations is discussed.

Animals↗

PubMed1975

[Deformities of the spine and ribs in embryologically related malformations of the heart with cyanosis].

Three cases of severe costovertebral deformities together with embryologically related cardiac malformations (Fallots Tetralogy and Truncus arteriosus communis) are presented. Two patients died because of their thoracic deformities and limited respiratory function. Relationships to similar bizarre veretebral anomalies are discussed. The cause is probably a teratogenic agent, acting between the fifth to eight embryologic week.

Abnormalities, Multiple↗

PubMed1997

Applied embryology in pediatric surgery.

The surgical correction of birth defects in the newborn is still a major challenge for pediatric surgeons. Approximately 3% of human newborns present with congenital malformations. In 1%, these malformations are so severe that immediate surgical intervention is necessary to save the affected newborns life. Morbidity remains high in some of these children with the necessity of repeated operations and hospitalizations despite a successful primary operation. As a consequence, in the United States today congenital malformations are the main cause of death in the neonatal period. This mortality shift indicates that gradually knowledge about congenital malformations lags behind the general progress clinical research has made in the surrounding fields. This is highlighted by the fact that detailed knowledge of the embryological background, the natural history and the teratology of many congenital defects is still unclear or controversial. In the past, progress in this field of research was hampered by small numbers of suitable normal human embryos of the various stages. Three-dimensional (3-D) reconstructions which are an essential component to investigate the development of structures like the foregut, the hindgut or the diaphragm, were technically difficult and time consuming to perform. Studies on abnormal development were not possible due to a paucity of appropriate embryos and young fetuses with congenital defects. However, recently some animal models have been developed applicable to embryological studies. We used these to elucidate the abnormal development of the hindgut and the diaphragm. An animal model for the study of abnormal foregut development will be available soon.

Animals↗

PubMed2000

Migration of intradural epidermoid matrix: embryologic implications.

The migratory behavior of acquired cholesteatoma matrices (those arising from the tympanic membrane) has been described previously. This tissue is derived embryologically from the first branchial groove and represents the only migratory epithelium arising from the branchial groove system. If the matrix from a cerebellopontine angle (CPA) epidermoid tumor exhibits migratory behavior similar to that of acquired cholesteatomas, a first branchial groove site of origin for CPA epidermoids would be supported. Intradural CPA epidermoid cells were grown in alpha-minimum essential medium. The cultures were examined daily, and cell mass migration rates were measured. It was observed that intradural epidermoid tumor matrix harvested from the CPA exhibited migration in vitro. Its migratory properties were indistinguishable from those of acquired cholesteatomas, which are embryologically derived from the first branchial groove. These data support the theory that purely intradural epidermoids are derived from cells of the first branchial groove.

Adult↗

PubMed2005

Adult mouse brain gene expression patterns bear an embryologic imprint.

The current model to explain the organization of the mammalian nervous system is based on studies of anatomy, embryology, and evolution. To further investigate the molecular organization of the adult mammalian brain, we have built a gene expression-based brain map. We measured gene expression patterns for 24 neural tissues covering the mouse central nervous system and found, surprisingly, that the adult brain bears a transcriptional "imprint" consistent with both embryological origins and classic evolutionary relationships. Embryonic cellular position along the anterior-posterior axis of the neural tube was shown to be closely associated with, and possibly a determinant of, the gene expression patterns in adult structures. We also observed a significant number of embryonic patterning and homeobox genes with region-specific expression in the adult nervous system. The relationships between global expression patterns for different anatomical regions and the nature of the observed region-specific genes suggest that the adult brain retains a degree of overall gene expression established during embryogenesis that is important for regional specificity and the functional relationships between regions in the adult. The complete collection of extensively annotated gene expression data along with data mining and visualization tools have been made available on a publicly accessible web site (www.barlow-lockhart-brainmapnimhgrant.org).

Algorithms↗

PubMed1996

The venous system of the lateral sellar compartment (cavernous sinus): an histological and embryological study.

The microanatomy of the lateral sellar or parasellar venous system (so-called cavernous sinus) is poorly understood and is still passionately debated. The exact nature of this venous structure is not yet clear whether it is a plexus or a sinus. In order to understand the anatomy of this area better, an embryological and adult microanatomical study was performed. Serial histological sections of human embryos and fetuses of well determined ages (6, 7, 8, 10, 11, 12, 14, 30 weeks) were used. The adult study was performed with microdissections and serial histological sections of laterosellar compartments. The analysis of this material confirms that the parasellar venous system is a true sinus, on the embryological and histological point of view. They differ from true veins. As other dural sinuses, it may contain different types of channels: from simple venous canal to complex venous plexus. The opinions of different authors are reviewed in the introduction and discussed with the results.

Adult↗

PubMed1992

Genetic research in embryology.

Based on findings on the molecular mechanisms of differentiation in drosophila, developmental genes have been identified in mammals similar to those in drosophila. Moreover, sequence similarities between drosophila developmental genes and mammalian growth factors provide evidence for common ancestors of such genes and suggest a complex link between growth and differentiation. As numerous oncogenes display their action as growth factors and are expressed during embryogenesis, differentiation and oncogenesis seem to be two sides of the same coin. Therefore, the aim of molecular embryology is twofold; elucidating differentiation processes and disclosing oncogenesis by studying the physiological function of oncogenes during development. Recent progress in molecular genetic technology now allows gene function to be studied by modification or disruption of genes. Models of clinical diseases have already evolved from such work and it is anticipated that progress in molecular embryology will further stimulate work on the diagnosis and therapy of genetic diseases as well as clinical oncology.

Animals↗

PubMed2006

Frozen embryo transfers: implications of clinical and embryological factors on the pregnancy outcome.

BACKGROUND: Frozen embryo transfers are characterized by impaired pregnancy outcome and increased incidence of pregnancy loss as compared with fresh IVF/ICSI embryo transfers. In this study, we performed a retrospective analysis of clinical and embryological factors that potentially influence the outcome of frozen embryo transfer. METHODS: We reviewed the outcome of 1242 frozen embryo transfers with respect to the age of the woman, the method of fertilization, embryo quality before and after freezing and the number of embryos transferred. RESULTS AND CONCLUSIONS: The pregnancy (positive hCG) and clinical pregnancy rates were 25.8 and 21.1%, respectively. A total of 107 (33.3%) of the 321 pregnancies identified by a positive hCG test miscarried either before (18.4%) or after (15%) the clinical recognition of gestational sac(s). The delivery rate for the frozen embryo transfers analysed was 17.2%. Our data revealed that the delivery rate after frozen embryo transfer was dependent on both the woman's age and the quality of embryos transferred, at the same time being unaffected by IVF/ICSI treatment. In addition, the increased woman's age at IVF/ICSI treatment was identified as the only parameter elevating the biochemical pregnancy rate, whereas the clinical abortion rate was found to be unrelated to the clinical or embryological parameters studied.

Adult↗

PubMed1997

The anatomy and embryological origins of the fascia of Denonvilliers: a medico-historical debate.

PURPOSE: We reviewed the conflicting theories concerning the anatomy and embryological derivation of Denonvilliers' fascia since its first description in 1836. MATERIALS AND METHODS: An extensive review of the literature for the last 160 years was done. RESULTS: Various studies contributed to the debate on the anatomy and origins of Denonvilliers' fascia. We chose to review these studies because of their sound methodology, large numbers of cases and results, and the high quality of the macroscopic and/or microscopic evidence. CONCLUSIONS: Denonvilliers' fascia consists of a single layer arising from fusion of the 2 walls of the embryological peritoneal cul-de-sac. Histologically, it has a double-layered quality. The fascia of Denonvilliers extends from the deepest point of the interprostatorectal peritoneal pouch to the pelvic floor. A so-called posterior layer is in reality the rectal fascia propria.

Anatomy↗

PubMed1996

Median cleft of the lower lip and mandible: case reports, a new embryologic hypothesis, and subdivision.

Median clefts of the lower lip and mandible are rare. In the literature so far, about 62 cases have been described. In addition, three more patients are presented here. These cases show a broad variation in the severity of this deformity, ranging from a simple notch in the vermillion to a complete cleft of the lip involving the tongue, the chin, the mandible, the supporting structures of the median of the neck, and the manubrium sterni. Several hypotheses concerning the pathogenesis of median clefts of the lip and mandible have been proposed. Most authors consider it to be a failure of fusion of the first pair of branchial arches or failure of mesodermal penetration into the midline. From our embryologic point of view, however, instead of paired branchial arches, only one first branchial arch develops during the early embryonic period (< or = 17 mm crown-rump length). Within this first branchial arch, two mandibular processes grow out, separated by a groove in the median. These mandibular processes do not fuse but merge during the late embryonic period (> or = 17 mm to < or = 60 mm crown-rump length). In the same developmental period, there is formation of the lip and the alveolar process and the anlage and outgrowth of one membrane bone center in each mandibular process, resulting in the formation of the mandible with its symphysis. As a consequence of the preceding, we propose the following subdivision of the median clefts of the lip and/or mandible: Hypoplasia of the mandibular processes during the early embryonic period will lead to the severest cleft of the mandible extending into the neck. During the late embryonic period, the less severe median clefts will develop. Disturbances of the outgrowth of bone centers of the mandible, resulting in nonformation of its symphysis, cause clefting of the mandible with involvement of all related soft tissues. Defects in the merging process produce just a notch of the vermilion or a higher cleft of the lower lip with or without involvement of the alveolar process of the mandible. In conclusion, the variety of the clefts in the median of the lower lip and/or mandible as well as the low rate of incidence can be explained by the embryologic hypothesis proposed here.

Female↗

PubMed1997

Embryological fusion between the ducts of the ventral and dorsal primordia of the pancreas occurs in two manners.

The junction between the main pancreatic duct and the accessory duct has been thought to be the site of fusion between the ducts of the ventral and the dorsal primordia of the pancreas. The aim of this study was to investigate the fusion point between the ventral and the dorsal pancreatic ducts and to determine whether there is any relationship between the configuration of the pancreatic ducts and the manner of embryological fusion. Pancreatography was performed at 22 consecutive autopsies. Immunohistochemical staining of pancreatic polypeptide (PP) was performed because PP cells were rich in the ventral pancreas but poor in the dorsal pancreas. We identified two types of fusion. In one type, the ventral and the dorsal pancreatic ducts fuse at their junction (one-point fusion). In the other type, the two ducts fuse not only at the proximal site but at a second, more distal site (two-point fusion). Analysis of the pancreatograms showed that the distance between the junction and the major papilla in two-point fusion is significantly shorter than in one-point fusion (p < 0.01). These results indicate a close correlation between the pattern seen on pancreatograms and the manner of embryological fusion.

Aged↗

PubMed1976

The embryology and management of vascular rings.

Among 34 patients with vascular rings, symptoms of tracheal and esophageal compression or both occurred during the first six months of life in 24 (71%). Diagnosis was made in all cases on either plain x-ray film or esophagogram, and was confirmed by operation or angiogram. Associated defects were numerous, with ventricular septal defect (5) and Down's syndrome (3) most common. Operative intervention was required in 18 cases (53%), including 12 of the 14 double arches. Only one of the ten patients with symptomatic recurrent subclavian artery underwent operation. Fourteen of the 18 patients operated upon had early total relief of symptoms, and 17 had excellent late results. A simple system for describing the embryology of vascular rings is presented, and the embryologic relationship between vascular rings and interrupted aortic arches is described. Because of frequent delay in recognition of vascular rings and other surgically correctable lesions, the work-up of every child with two or more episodes of pneumonia should include barium swallow.

Adolescent↗

PubMed2005

Congenital auricular anomalies: topographic anatomy, embryology, classification, and treatment strategies.

Congenital auricular anomalies are heterogeneous, with various descriptive and eponymous terms being used. Current classification systems are useful in guiding surgical treatment of severe anomalies. However, they do not generally account for the less severe anomalies, which form the majority of congenital auricular anomalies, nor their contemporary treatment. In this article, the authors review the anatomy and embryology of the external ear and propose a simple classification of congenital auricular anomalies that encompasses all forms of congenital auricular anomalies, facilitates proper diagnosis, and guides treatment. Congenital auricular anomalies should be classified as malformational or deformational anomalies. Malformational auricular anomalies are caused by embryologic maldevelopment that occurs between the fifth and ninth week of gestation resulting in deficient and/or supernumerary auricular components. Deformational auricular anomalies result from in utero or ex utero deformational forces, including those caused by an aberrant insertion of the intrinsic or extrinsic auricular muscles. Malformational auricular anomalies generally require surgical correction during childhood or adolescence. For practical purposes, deformational auricular anomalies have a full complement of chondrocutaneous components that can be digitally manipulated to a normal shape. These anomalies are best treated by auricular molding, which is effective if it is initiated within the first 3 months of life. Deformational auricular anomalies are best regarded as a pediatric public health issue and are best managed nonsurgically. Education of neonatal pediatricians, obstetricians, family doctors, and midwives will allow proper early diagnosis of all congenital auricular anomalies, which is vital to appropriate treatment. These practitioners should be encouraged to manage deformational auricular anomalies early in life so that surgery can be largely avoided in these patients.

Congenital Abnormalities↗

PubMed2001

Founding editorial: embryology--an integrated approach.

We introduce the Embryology domain of TheScientificWorld and outline the scope and aims. We argue for an interdisciplinary approach to problems in develop-mental biology. Three areas are identified as being of particular relevance to this domain: evolutionary developmental biology, teratology, and descriptive or experimental embryology.

Animals↗