Embryological Facts Research Articles

Some embryological facts on ectopic liver tissue in the umbilical cord

Some embryological facts on ectopic liver tissue in the umbilical cord

The position of the duodenojejunal junction: the wrong horse to bet on in diagnosing or excluding malrotation

The purpose of this communication is to highlight the shortcomings of all currently used imaging criteria in diagnosing or excluding malrotation and offer ultrasound demonstration of the 3(rd) portion of the duodenum (D3) between the AO and the SMA in transverse and sagittal plains as the most reliable diagnostic method. Although UGI is currently considered to be the imaging modality of choice in diagnosis of malrotations, numerous publications indicate that in certain patients, false positives and negatives can be encountered. The material consists of more than 10 years experience in university settings, during which the author has used US as the definitive imaging modality for the work-up of malrotation. High resolution linear transducers (5-17 MHz) are the transducers of choice. Imaging plains: A. Transverse. With gradual grading compression, the following landmarks are illustrated in cehaplocaudad directions in the following order. The junction of splenic vein with the SMV portal vein. The cross sections of SMA and SMV that may either be situated in midline, or to the right or the left of the midline. Left renal vein crossing the spine from left to right between the AO and the SMA. The jejunal vein, often coming from left, transversing between the AO and the SMA. The transverse portion of the duodenum, D3, between the AO & the SMA. B. Sagittal. D3 between vertically oriented SMA-SMV and the AO. If SMA is not aligned with the AO by slight compression on the right or the left side of the abdomen, it will be aligned (depending on leftward or rightward position of SMA-SMV in axial plain). Vertical orientation of SMA and SMV if they have an anteroposterior orientation. C. Coronal. Side by side orientation of SMA and SMV if they don't have an anteroposterior orientation. In overwhelming majority of cases, by illustrating a retromesenteric D3 malrotation and, therefore, midgut volvulus were excluded. None of the current imaging criteria addresses the following most fundamental anatomic and embryologic facts regarding the gut rotation and fixation. In first trimester, the D3 is secured in retroperitoneal space after the embryologic journey comes to an end, making the duodenum immune of midgut volvulus. The surgical pathology of malrotation-midgut volvulus indicates that D3 is always Intraperitoneal and has not reached its final embryologic destination in retroperitoneal space. Demonstrating a retromesenteric D3, therefore, indicates that the embryologic journey is completed and the patient does not have malrotation. Excluding malrotation excludes the likelihood of midgut volvus. The position of the DJJ, the configuration of the duodenal sweep, the orientation of the mesenteric vessels are all wrong horses to bet on because none of them addresses the fundamental anatomic and embryologic facts. Only the cross-sectional imaging, US, CT and MRI can prove that the D3 is retromesenteric, therefore, excluding malrotation and volvulus. Therefore, demonstrating a retromesenteric duodenum is the reference standard of imaging in the work-up of malrotation, not any other previously published criteria. The US imaging is the most acceptable imaging method for malrotation work-up, in the spirit of ALARA principle and "Image Gently" campaign.

Ontogenetic development of the helical heart: concepts and facts

The structural and functional organization of the ventricular myocardial mass is a controversial matter that cannot be resolved by anatomical studies alone. Therefore, other approaches such as investigations of the ontogenetic development of the ventricular myocardium might help to resolve controversies about its structural and functional organization. It has recently been proposed that the spatial orientation of Torrent-Guasp's ventricular myocardial band model (basal and apical loops) might be the mature morphological correlate of twists and torsions of the embryonic heart loop. In the present contribution, the suggestions made in this concept were analyzed in the light of currently known facts about the development of the embryonic heart. It was found that some of the suggestions made in this concept do not correspond to embryological facts, whereas other suggestions could neither be disproved nor confirmed on the basis of our current knowledge on heart development. The answer to the question as to which of the various models of myocardial fibre organization fits best with the ontogenesis of the myocardial mass awaits future studies. The myocardial units of Torrent-Guasp's myocardial band model are said to have a functional rather than a morphological personality. Future studies on the ontogenetic development of the myocardium, therefore, should comprise not only anatomical analyses of dead specimens but should additionally comprise high resolution in vivo analyses of the development of the spatio-temporal contraction patterns of embryonic and fetal hearts.

Bildgebende Diagnostik bei Milzerkrankungen

Primary diseases of the spleen are relatively rare. More frequently, the spleen is involved secondarily in hematological, oncological, infectious, immunological, vascular, and other systemic diseases. The spleen is the most commonly injured organ in blunt abdominal trauma. Anatomical and physiological basics are explained, in addition to embryological facts with resulting abnormalities, such as accessory and "wandering" spleen, and polysplenia. The most frequent primary and secondary diseases of the spleen, including rare diagnoses, are presented and illustrated. Hemangioma represents the most common primary benign tumor, and lymphoma the most common primary malignant tumor of the spleen. Diagnostic imaging does not a allow safe differentiation between Hodgkin's and non-Hodgkin's lymphoma. One section deals with the clinical value and diagnostic workup of incidentally detected lesions. Simple cysts and calcifications need neither clarification nor a follow-up examination. Atypical cysts should be controlled within 3-6 months. Additional clarification using CT or MRT should be reserved for cases with a strong suspicion of clinically relevant primary or secondary splenic disease.

Reversed rotation of the gut incidental to cholecystitis in a left-sided gall-bladder.

Abstract A patient with reversed rotation of the midgut loop of the retro-arterial colon type is reported. She is unique in being the first case recorded in the literature with a right-sided colon and a left-sided liver without situs inversus of the abdominal viscera. An explanation of the findings is suggested, based on known embryological facts. Previous reports indicate that patients with reversed rotation all present with obstructive symptoms secondary to the altered anatomy. This patient is unusual in that her symptoms and pathology were unrelated to the anatomical abnormality.

Neck cysts, sinuses, thyroglossal duct cysts, and branchial cleft anomalies

Unlike benign masses in other locations where simple excision is often the preferred method of diagnosis, such an approach in the neck may result in chronic infection and draining tracts. The surgical approach to pediatric neck masses requires a thorough understanding of the diagnostic possibilities and the anatomic implications before making the incision. Sistrunk understood this dilemmaafterobservinghighrecurrencerateswithremoval of thyroglossal duct cysts. His operation, published in 1928, 1 was based on the anatomic and embryologic facts ofthyroiddescentthroughoraroundthehyoidbone.The combination of accurate preoperative diagnosis and specific anatomic knowledge remains the standard for neck surgery today. Fortunately, the preoperative diagnostic evaluation is straightforward, and when followed, operative outcomes are excellent. 2

When do human beings begin? scientific myths and scientific facts

Outlines some basic human embryological facts and considers several myths such as “the immediate product of fertilization is just a potential human being”. Gives medical facts to clarify these issues and concludes that these have far reaching implications for many areas of research. Argues that these decisions, at present, are based more on myth than science.

The Weigert-Meyer Law Demystified

After reviewing the various hypotheses that have been put forward to attempt to explain the Weigert-Meyer Law, a new, simple, and attractivc explanation, based on embryological facts, is offered (with illustrative drawings). We hope it will dissipate the mystery of the Weigert-Meyer Law.

A giant lateral cervical cyst

The Branchial apparatus was first described by Von Baer in 1827. (cited by King. 1949) After five years the cervical fistula was recognised as an anomalie of Branchial apparatus. By 1864 the term “branchial fistulae” had been applied, and soon thereafter cysts of the lateral neck were to be ascribed to branchial origin. Everything appeared to fit nicely into this neat categorization until 1912 when Wenglowski published the results of his dissections of Cadavers and human embryos, which led him to doubt the branchiogenic origin of many lateral cervical cysts. In the ensuing years various theories as to the exact pathogenesis of these anomalies have been proposed with more controversies on the matter of cysts than on fistulas or sinuses. There are four theories of origin of branchial cysts but because of the complicated development of the neck none has been proven by empryological investigation. Most of the theories attempted to correlate clinical findings with known embryological facts and none can stand close scrutiny4. Here a case is reported who presented to us with large lateral cervical cyst extending from angle of jaw to sternoclavicular joint, strengthening the cervical sinus theory. It postulates that branchial cysts represent remains of the cervical sinus of His which is formed by the second arch growing down to meet the fifth.

Split Cord Malformation

MUCH CONFUSION STILL exists concerning the pathological definitions and clinical significance of double spinal cord malformations. Traditional terms used to describe the two main forms of these rare malformations, diaste-matomyelia and diplomyelia, add to the confusion by their inconsistent usage, ambiguities, and implications of their dissimilar embryogenesis. Based on the detailed radiographic and surgical findings of 39 cases of double cord malformations and the autopsy data on two other cases, this study endorses a new classification for double cord malformations and proposes a unified theory of embryogenesis for all their variant forms and features. The new classification recommends the term split cord malformation (SCM) for all double spinal cords. A Type I SCM consists of two hemicords, each contained within its own dural tube and separated by a dura-sheathed rigid osseocartilaginous median septum. A Type II SCM consists of two hemicords housed in a single dural tube separated by a nonrigid, fibrous median septum. These two essential features necessary for typing, the state of the dural tube and the nature of the median septum, do not ever overlap between the two main forms and can always be demonstrated by imaging studies so that accurate preoperative typing is always possible. All other associated structures in SCM such as paramedian nerve roots, myelomeningoceles manqué, and centromedian vascular structures frequently do overlap between types and are not reliable typing criteria. The unified theory of embryogenesis proposes that all variant types of SCMs have a common embryogenetic mechanism. Basic to this mechanism is the formation of adhesions between ecto- and endoderm, leading to an accessory neurenteric canal around which condenses an endomesenchymal tract that bisects the developing notochord and causes formation of two hemineural plates. The altered state of the emerging split neural tube and the subsequent ontogenetic fates of the constituent components of the endomesenchymal tract ultimately determine the configuration and orientation of the hemicords, the nature of the median septum, the coexistence of various vascular, lipomatous, neural, and fibrous oddities within the median cleft, the high association with open myelodysplastic and cutaneous lesions, and the seemingly unlikely relationship with fore and midgut anomalies. The multiple facets of this theory are presented in increasing complexity against the background of known embryological facts and theories; the validity of each facet is tested by comparing structures and phenomena predicted by the facet with actual radiographic, surgical, and histopathological findings of these 41 cases of SCM.

Die Arteria radialis superficialis

During the clinical investigation of 570 soldiers of the German army, we were not able to feel the pulse in 5 cases at the typical place of the radial pulse in the distal part of the forearm. In these 5 cases we were able to find a subcutaneous artery which coursed superficial to the anatomical snuffbox and crossed superficial to the tendon of the extensor pollicis longus muscle. This superficial radial artery enters the deep aspect of the palm between the first and the second metacarpale bones. In three cases we found a bilateral occurrence of this artery, the other variations were observed unilaterally, two on the right side and one on the left side of the forearm. In the family of two patients other members were found who had the same variation of the radial artery. In one of the cases an arteriography of the vessels was made to find the exact anatomical course of the observed variation. We compared our results with the literature on this variation of the radial artery and found agreement on the following course for this vessel. The radial artery divides in the distal fourth of the forearm (5–7 cm proximal to the wrist joint) into two branches. The dorsal branch courses subcutaneously over the tendon of the brachioradialis muscle and runs over the tendon of the extensor pollicis longus muscle to enter the deep aspect of the palm in the first metacarpal space. This dorsal branch courses parallel to the superficial branch of the radial nerve. The palmar branch can be regarded as the ‘normal’ radial artery, which continues along the medial border of the brachioradialis muscle and courses deep under the tendons of the dorsal muscles of the thumb. The rare appearance (frequency ∼1%) of a superficial radial artery in man has probably some phylogenetic importance. This is proven by studies on the comparative anatomy of mammals. This variation of the radial artery seems to be homologous to the superficial radial artery which is described in many lower mammals. In human embryos a superficial radial artery is found as well which courses parallel to the superficial branch of the radial nerve and ends on the dorsal side of the hand. Taking all the anatomical and embryological facts into consideration we propose to name this variation of the radial artery the ‘arteria radialis superficialis’.

Anomalies of Heart, Spleen, Kidneys, Gut, and Limbs May Result from an Overdistended Neural Tube: A Hypothesis

A hypothesis is advanced that many congenital anomalies of non-neural organs may be produced by damage to their mesodermal or entodermal anlagen caused by overdistention of the embryonic neural tube. Evidence to support the hypothesis derives from: (1) seldom appreciated but unequivocal embryologic facts about prechoroid plexus neural tube morphogenesis; (2) an understanding of the role of neural tube overdistention in the production of various dysraphic conditions; (3) the frequency of association of non-neural anomalies with dysraphic conditions; and 4) an analysis of the anatomic features of the organ anomalies associated with dysraphism. The practical utility of the hypothesis is that (1) it helps explain a seemingly widely divergent subset of phenomenology and (2) it is testable. At present, treatment of children with congenital anomalies is largely palliative. Prevention of these distressing defects in the future will only be realizable if the mechanisms of their genesis are more clearly understood.

Arterial anomalies at the base of the skull.

Six arterial anomalies at the base of the skull are reported. Five of these concern the course, or the filling, of the middle meningeal artery. After correlation with basic anatomical and embryological facts it appears that a satisfactory embryological explanation, based on regressions and reversal of flux, may be proposed.

Carpal tunnel syndrome caused by the persistence of the median artery.

As another cause for a symptomatic carpal tunnel syndrome the persistence of the median artery is postulated. This was observed by the authors in three cases all of whom presented a typical carpal tunnel syndrome. As the only cause in all three cases a persistent median artery was observed. The embryological facts and the possible pathogenetic causes discussed.

UNUSUAL CAUSE OF BROWN-SEQUARD SYNDROME.

With few exceptions 4 most authors consider that the several varieties of rachischisis are due to defective closure of the dorsal aspect of the neural tube. 2,5 This theory is not only in accord with the embryological facts but also explains why the closure defects are almost exclusively present in the dorsal aspect of the neural axis. Anterior defects are rare but by no means unknown. Such defects are usually present as anterior meningoceles 3,8 or sinus tracts connecting the neural axis to the enteric tube. 6,7 The case to be reported here is quite unique. A small herniation of the thoracic spinal cord through a defect in the dura mater was found. The patient presented himself with a modified Brown-Sequard syndrome. Perusal of the literature has failed to reveal the presence of any similar case. Report of Case This 33-year-old man was referred to the neurosurgical service of the

Testicular tubular adenoma in two sisters

1.1. Two cases of benign testicular tubular adenoma in two sisters are reported. The gonads consisted preponderantly of testicular tissue; the ovarian tissue was represented only by islands of ovarian stroma. In spite of the predominantly male character of the gonads, the patients looked and felt perfectly feminine. Each sister had female external genitals, a vagina, but no or almost no uterus and only a tiny tubal rudiment.2.2. The removal of the malformed gonads caused severe deficiency symptoms.3.3. The genealogic tree of these sisters showed that several members had abnormalities of their sexual organs and their sexual personality which marked them as intersexual individuals.4.4. The gonads of these cases are interpreted as ovotestes. Embryologic facts as well as Goldschmidt's intersexuality theory are applied to explain the origin of this malformation.

Congenital branchiogenic anomalies: A report of 82 cases

The embryology of the branchial system of arches, pouches and clefts is briefly reviewed. From a correlation of embryologic facts and clinical findings in cases of lateral fistulae and cysts of the neck it is believed that these lesions develop most commonly from the second branchial cleft and branchial pouch. The congenital sinuses of the ear and preauricular region are believed to develop from an incomplete fusion of the lobules which normally coalesce to form the ear. Lateral, cartilaginous pedunculated or sessile tabs of the neck would appear to represent anomalous formations from the second or third branchial arch. The symptoms of auricular or lateral cervical sinuses are referable to: (1) discharge of mucoid material originating in the lining membrane; (2) discharge of desquamated cells from the lining epithelium if this be of the squamous type; or (3) recurring local inflammation. The lateral congenital cysts of the neck may be troublesome because of local swelling, of recurring infection, or because of reflex disturbances by pressure on the vagus nerve. The cartilaginous rests of the neck are important only from the point of view of cosmetic disfigurement. The small auricular and preauricular sinuses can be treated by injection of sclerosing fluids or by endothermy coagulation. When there has been recurrent infection in a preauricular sinus with consequent destruction of subcutaneous tissue, the lesion is best treated by excision. If a cervical fistula is small and has little discharge, no treatment is necessary, but if the discharge is bothersome, or if there has been repeated infection, the entire tract should be excised. A lateral cervical cyst should be excised, and any tract communicating with it should also be removed. The operative incision for the neck lesions should never be parallel to the sternocleidomastoid muscle, but should always be made in the direction of the neck folds. In those cases in which extensive dissection of the neck is necessary, adequate exposure can be obtained by the use of two horizontal incisions placed in a stair step fashion. When such incisions are carefully closed and the skin edges are approximated with continuous subcuticular sutures, the resulting scars are minimal and are almost invisible.

MICROCEPHALIA VERA

Microcephalia vera, as pathologic entity, has become better understood during the past few decades owing to the cooperation of the clinicians, the embryologists and the pathologists. The clinicians have added to the literature on the subject many instructive case reports which have thrown enlightenment on the physical aspects, anthropometric measurements, neurologic and psychiatric deviations, etc., all of which have increased knowledge of the results of defective development of the brain during intra-uterine life. From the pathologic studies of the condition one can determine the relationship between the pathologic picture disclosed in the central nervous system and comparable embryologic facts relating to teratologic formations during the embryonic development of the cerebral hemispheres. Furthermore, one wishes to inquire into the process of formation of the so-called heterotopias and the anomalies of the cerebral cortex during its earliest elaboration. HISTORICAL REVIEW AND THEORIES OF MICROCEPHALY Microcephaly is defined as a condition or

FASCIAE OF THE UROGENITAL TRIANGLE

Before proceeding to a discussion of the anatomy of the perineum, it is interesting to note that the pure anatomist has no counterpart for some of the terms used by the surgeon. Denonvilliers' fascia, the rectourethralis muscle, Buck's fascia and Colles' fascia are surgical terms used to designate conveniently certain anatomic landmarks which to the anatomist are not definite structures. The lack of liaison between the dissecting room and the operating amphitheater is responsible for much of our inaccurate knowledge and bizarre perineal surgery. Probably because of the hardened fasciae in embalmed bodies, there is a tendency for the dissector to consider the urogenital diaphragm as the keystone of the perineum, the other structures being formed secondarily, and to discredit all theories that do not presuppose the presence of a primary rigid double walled triangular membrane perforated by the urethra. This is largely an assumption which the embryologic facts as

SOME OPHTHALMOLOGIC MANIFESTATIONS OF DISEASES OF THE NERVOUS SYSTEM

The ophthalmologic manifestations of diseases of the nervous system have long occupied a conspicuous place, and have been studied with great interest by the neurologist and the ophthalmologist. Realizing the close relation existing between the eye and the brain, the retina being an outgrowth from the rudimentary brain of the primary optic vesicle, and the optic nerves being portions of the lobes of the brain, 1 and admitting that these anatomic and embryologic facts are true, one readily realizes how the early manifestations of diseases of the brain may reveal themselves through the medium of the eye, which is the principal means we have of noting the changes resulting from disease of this organ. On examining the eye, we are able, in many cases, to see these changes in their incipiency, and thus make an intelligent diagnosis of the workings of this great machine (consisting of 600 million cells) before