Normal and abnormal embryonic development of the anorectum in human embryos

Delphi Consensus on Diagnostic Criteria for LUMBAR Syndrome

OBJECTIVE

To develop consensus on diagnostic criteria for LUMBAR syndrome, the association of segmental infantile hemangiomas that affect the Lower body with Urogenital anomalies, Ulceration, spinal cord Malformations, Bony defects, Anorectal malformations, Arterial anomalies and/or Renal anomalies.

STUDY DESIGN

These diagnostic criteria were developed by an expert multidisciplinary and multi-institutional team based on analysis of peer-reviewed data, followed by electronic-Delphi consensus of a panel of 61 international pediatric specialists.

RESULTS

After two Delphi rounds, a 92% or higher level of agreement was reached for each Delphi statement. 98% of panelists agreed with the diagnostic criteria, and 100% agreed the criteria would be useful in clinical practice. The diagnosis of LUMBAR requires the presence of a segmental, or patterned, infantile hemangioma of the lumbosacral, sacrococcygeal, or pelvic cutaneous regions plus one additional criterion of the urogenital, spinal, bony, anorectal, arterial, or renal organ systems.

CONCLUSIONS

These diagnostic criteria will enhance clinical care by improving screening, detection, and overall awareness of this poorly understood neurocutaneous disorder. The criteria can be utilized by a wide variety of pediatric subspecialists. In addition, formal criteria will improve phenotypic uniformity among LUMBAR syndrome cohorts and a patient registry, allowing investigators to assess clinical features, long-term outcomes, and results of genetic sequencing in a standardized manner. Finally, these criteria will serve as a starting point for prospective studies to establish formal screening and management guidelines.

Single-cell guided prenatal derivation of primary fetal epithelial organoids from human amniotic and tracheal fluids

Isolation of tissue-specific fetal stem cells and derivation of primary organoids is limited to samples obtained from termination of pregnancies, hampering prenatal investigation of fetal development and congenital diseases. Therefore, new patient-specific in vitro models are needed. To this aim, isolation and expansion of fetal stem cells during pregnancy, without the need for tissue samples or reprogramming, would be advantageous. Amniotic fluid (AF) is a source of cells from multiple developing organs. Using single-cell analysis, we characterized the cellular identities present in human AF. We identified and isolated viable epithelial stem/progenitor cells of fetal gastrointestinal, renal and pulmonary origin. Upon culture, these cells formed clonal epithelial organoids, manifesting small intestine, kidney tubule and lung identity. AF organoids exhibit transcriptomic, protein expression and functional features of their tissue of origin. With relevance for prenatal disease modeling, we derived lung organoids from AF and tracheal fluid cells of congenital diaphragmatic hernia fetuses, recapitulating some features of the disease. AF organoids are derived in a timeline compatible with prenatal intervention, potentially allowing investigation of therapeutic tools and regenerative medicine strategies personalized to the fetus at clinically relevant developmental stages.

Distal vaginal atresia: a report of a rare type found a late-term fetus and its histological comparison with the normal pelvis

Solitary distal vaginal atresia is generally caused by a transverse septum or an imperforate hymen. We found a novel type of distal vaginal atresia in a late-term fetus (gestational age approximately 28 weeks) in our histology collection. This fetus had a vaginal vestibule that was closed and covered by a thick subcutaneous tissue beneath the perineal skin in the immediately inferior or superficial side of the imperforate hymen. The uterus, uterine tube, anus, and anal canal had normal development. The urethral rhabdosphincters were well-developed and had a normal topographical relationship with the vagina, but the urethrovaginal sphincter was absent. Thus, vaginal descent seemed to occur normally and form the vestibule. However, the external orifice of the urethra consisted of a highly folded duct with hypertrophied squamous epithelium. Notably, the corpus cavernosum and crus of the clitoris had poor development and were embedded in the subcutaneous tissue, distant from the vestibule. Normally, the cloacal membrane shifts from the bottom of the urogenital sinus to the inferior aspect of the thick and elongated genital tubercle after establishment of the urorectal septum. Therefore, we speculate there was a failure in the transposition of the cloacal membrane caused by decreased elongation of the genital tubercle. The histology of this anomaly strongly suggested that the hymen does not represent a part of the cloacal membrane, but is instead a product that appears during the late recanalization of the distal vagina after vaginal descent. The transverse septum was also likely to form during this recanalization.

First trimester lower abdominal cysts as early predictor of anorectal malformations

INTRODUCTION

Prenatal ultrasound diagnosis of anorectal malformations (ARMs) is challenging and often missed as direct visualization of the anal sphincter is not routinely performed, plus the technique is operator-dependent and inaccurate, also in expert hands. Other indirect signs, such as rectosigmoid overdistension or intraluminal calcifications, are occasionally present in late pregnancy. The detection of a cyst of the lower abdomen in the first trimester may be an early sign of ARM. Here we reported our experience and a review of the literature of such cases.

MATERIAL AND METHODS

Isolated cases of lower abdomen cysts encountered in the first trimester at the Prenatal Diagnosis Unit during the last 5 years were retrieved and compared with those found in literature. Post-natal clinical data were analyzed to check the presence and type of malformations.

RESULTS

A total of three cases of lower abdomen cysts were found in our center and 13 in literature. In our case series all the cysts spontaneously regressed and were no longer visible since the second trimester of pregnancy, while in literature this was reported in only 4 out of 13 cases. ARM was confirmed in all patients at birth or post-mortem.

CONCLUSIONS

The finding of a lower abdomen cyst during the first trimester of pregnancy could be an early predictive sign of ARM, even if it disappears during pregnancy. In these cases, we suggest mentioning to the parents the possibility of an ARM during the counseling and to refer the couple to a Colorectal Center.

Embryology and anatomy of anorectal malformations

The etiology of anorectal malformations (ARM) is complicated because of the spectrum of anomalies seen clinically, many of which are isolated and seemingly unique. Recent studies suggest that ARMs result from abnormal cloacal membrane (CM) development that contributes to disrupt normal local muscle and nerve development. If CM maldevelopment is severe, the rectal pouch lies above the pelvic floor, resulting in asymmetric and/or deviated musculature, so a midline incision is likely to cause trauma or be detrimental. Autonomic nerve plexuses can be associated with a fistula tract in ARMs and are also at risk for damage during surgery and contribute to genitourinary complications. Understanding the anatomy and development of the perineum is crucial for treating the broad spectrum of anomalies associated with ARMs and may assist in predicting/managing other related morbidity.

Early Diagnosis of Anal Canal Duplication: The Importance of a Physical Examination

Anal canal duplication (ACD) is an extremely rare congenital anomaly of the intestinal tract that presents as an extra opening of the anal canal without communication with the anorectum. We present the case of a five-year-old male presenting to the pediatrician without symptoms and upon physical examination, a duplicated anal canal along the midline was discovered. The patient was admitted for surgery and the canal was removed via mucosal stripping. Postoperatively, the patient recovered well. The present study aims to expand on our knowledge of a very rare pathological entity and emphasize the importance of a complete pediatric physical examination.

Anal Canal Duplication Mimicking Recurrent Abscess: A Case Report and Review of the Literature

Background

Anal canal duplication (ACD) is a very rare duplication of the gastrointestinal tract and is described as a secondary anal orifice along the posterior side of the normal anal canal. Early surgical removal is advisable, also in asymptomatic patients, because of the risk of inflammatory complications, such as recurrent crissum abscess, and malignant changes.

Case presentation

A previously healthy 2-year-old boy was evaluated in the emergency department with fever. He complained of anal pain in the absence of incentive. Physical examination and ultrasound confirmed a diagnosis of perianal abscess. He was treated with incision and drainage of the abscess and intravenous antibiotics. Two months after his discharge from the hospital, he developed fever and had intervals discharge pus and pain in the same locations. Colorectal endoscopy revealed that there was no fistula opening at the rectal wall. Intraoperative fistulography showed a fistulous tract that was connected to a subcutaneous cavity. Excision of the fistulous tract and wide drainage of the deep postanal space were performed. The patient was referred to our hospital for further evaluation 6 months later. Physical examination showed a secondary anus that had not been noticed before. MRI showed an anal fistula between 1 and 3 o’clock, and preoperative fistulography revealed a 3-cm-long tubular structure without any connection with the rectum. The diagnosis of ACD was made by intraoperative examination with a metal catheter and the postoperative pathological analysis. The duplicated anal canal was resected completely via a perianal approach without any rectal injury. Histology showed a squamous epithelium in the distal end with some smooth-muscle fibers. After a follow-up of 8 months, the patient has been doing well.

Conclusion

Recurrent crissum abscess should raise clinical attention to alimentary tract congenital malformations such as ACD. Prompt recognition of these unique presentations of ACD is needed, and complete excision through a perineal approach or posterior sagittal approach is recommended.

PREGNANCY AND ANORECTAL MALFORMATIONS

A wide range of pathology from ectopia of the anal opening to combined anomalies of the rectum and genitourinary tract refers to malformations of the anorectal region. Since the results of their treatment, both long-term and short-term, are not always satisfactory, the course of pregnancy can worsen the condition of the pregnant woman and affect the intrauterine fetus. This circumstance provides for the management of childbirth in a specialized institution.

Can Anorectal Atresia Be Diagnosed in the First Trimester of Pregnancy? A Systematic Literature Review

Anorectal atresia (ARA) is a common congenital anomaly, but prenatal diagnosis is difficult, late, and unspecific. Utilizing a case of a 46 year old primipara with an egg donation In Vitro Fertilization (IVF) pregnancy, diagnosed at the first trimester scan with an anechoic isolated structure, which indicates anal atresia, we performed a systematic literature review in order to evaluate early prenatal ARA diagnosis. A total of 16 cases were reported as first trimester ARA suspicion, and only three had no associated anomalies. The most frequent ultrasound (US) sign was the presence of a cystic, anechoic pelvic structure of mainly tubular shape, or a plain abdominal cyst. In the majority of cases, structures were thin-walled and delimitated from the bladder. The presence of hyperechoic spots signifying enterolithiasis and peristaltic movements were helpful in order to establish the bowel origin of the lesion. Considering the high eventuality that the lesion is transitory, meaning later in pregnancy the fetus looks normal, early detection of such a sign should prompt further structural detailed evaluation, karyotyping, and appropriate pregnancy and postnatal counselling.

Regulatory roles of epithelial-mesenchymal interaction (EMI) during early and androgen dependent external genitalia development

Development of external genitalia (ExG) has been a topic of long mystery in the field of organogenesis research. Early stage male and female of mouse embryos develop a common genital tubercle (GT) in the perineum whose outgrowth extends distally from the posterior cloacal regions. Concomitant with GT outgrowth, the cloaca is divided into urogenital sinus and anorectum by urorectal septum (URS) internally. The outgrowth of the GT is associated with the formation of endodermal epithelial urethral plate (UP) attached to the ventral epidermis of the GT. Such a common developmental phase is observed until around embryonic day 15.5 (E15.5) morphologically in mouse embryogenesis. Various growth factor genes, such as Fibroblast growth factor (Fgf) and Wnt genes are expressed and function during GT formation. Since the discovery of key growth factor signals and several regulatory molecules, elucidation of their functions has been achieved utilizing mouse developmental models, conditional gene knockout mouse and in vitro culture. Analyses on the phenotypes of such mouse models have revealed that several growth factor families play fundamental roles in ExG organogenesis based on the epithelial-mesenchymal interaction (EMI). More recently, EMI between developing urethral epithelia and its bilateral mesenchyme of later stages is also reported during subsequent stage of androgen-dependent male-type urethral formation in the mouse embryo. Mafb, belonging to AP-1 family and a key androgen-responsive mesenchymal gene, is identified and starts to be expressed around E14.5 when masculinization of the urethra is initiated. Mesenchymal cell condensation and migration, which are regulated by nonmuscle myosin, are shown to be essential process for masculinization. Hence, studies on EMI at various embryonic stages are important not only for early but also for subsequent masculinization of the urethra. In this review, a dynamic mode of EMI for both early and late phases of ExG development is discussed.

The development of the cloaca in the human embryo

Subdivision of cloaca into urogenital and anorectal passages has remained controversial because of disagreements about the identity and role of the septum developing between both passages. This study aimed to clarify the development of the cloaca using a quantitative 3D morphological approach in human embryos of 4–10 post‐fertilisation weeks. Embryos were visualised with Amira 3D‐reconstruction and Cinema 4D‐remodelling software. Distances between landmarks were computed with Amira3D software. Our main finding was a pronounced difference in growth between rapidly expanding central and ventral parts, and slowly or non‐growing cranial and dorsal parts. The entrance of the Wolffian duct into the cloaca proved a stable landmark that remained linked to the position of vertebra S3. Suppressed growth in the cranial cloaca resulted in an apparent craniodorsal migration of the entrance of the Wolffian duct, while suppressed growth in the dorsal cloaca changed the entrance of the hindgut from cranial to dorsal on the cloaca. Transformation of this ‘end‐to‐end’ into an ‘end‐to‐side’ junction produced temporary ‘lateral (Rathke's) folds’. The persistent difference in dorsoventral growth straightened the embryonic caudal body axis and concomitantly extended the frontally oriented ‘urorectal (Tourneux's) septum’ caudally between the ventral urogenital and dorsal anorectal parts of the cloaca. The dorsoventral growth difference also divided the cloacal membrane into a well‐developed ventral urethral plate and a thin dorsal cloacal membrane proper, which ruptured at 6.5 weeks. The expansion of the pericloacal mesenchyme followed the dorsoventral growth difference and produced the genital tubercle. Dysregulation of dorsal cloacal development is probably an important cause of anorectal malformations: too little regressive development may result in anorectal agenesis, and too much regression in stenosis or atresia of the remaining part of the dorsal cloaca.

MSX2 and BCL2 expressions in the development of anorectal malformations in ethylenethiourea-induced rat embryos

BACKGROUND

This study aimed to determine Msh homeobox 2 (MSX2) and B cell lymphoma-2 (BCL2) expression patterns during anorectal development in anorectal malformations (ARM) and normal rat embryos, with the goals of determining the role of MSX2 and BCL2 in ARM pathogenesis.

METHODS

ARM was induced in rat embryos with ethylenethiourea administered to dams on gestational day 10 (GD10). Embryos were harvested by cesarean deliveries from GD14 to GD16. MSX2 and BCL2 expression was evaluated via immunohistochemical staining, immunofluorescence, western blotting and quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Immunohistochemical staining of ARM embryos revealed that MSX2 was mainly expressed in the epithelium of the hindgut and urorectal septum (URS) on GD14. On GD15 and GD16, MSX2-immunolabeled cells were noted in the epithelium of the rectum, fistula and URS. However, in normal embryos, faint immunopositivity for MSX2 was demonstrated in the epithelium of the rectum and URS from GD14 to GD16. As for BCL2, in normal embryos, BCL2-immunopositive cells were extensively expressed in the epithelium of the hindgut and URS on GD14 and GD15. In ARM embryos, weak immunopositivity for BCL2 was detected in the epithelium of hindgut and URS on GD14 and GD15. Immunofluorescence revealed that MSX2 and BCL2 colocalized in the hindgut. In ARM embryos, we observed more MSX2-positive than BCL2-positive cells on GD14; the normal embryos had the opposite pattern. Analyses by western blot and qRT-PCR showed that MSX2 protein and mRNA expression was significantly increased in ARM embryos compared with the normal embryos on GD15 and GD16 (p < 0.05). However, BCL2 protein and mRNA expression was significantly decreased in ARM embryos compared with the normal embryos on GD14 (p < 0.05). The MSX2/BCL2 ratio of protein and mRNA expression level in the ARM group was the highest on GD15.

CONCLUSION

These results indicate that upregulation of MSX2 and downregulation of BCL2 during cloacal development into the rectum and urethra might be related to the ARM development, and MSX2 promoted apoptosis through reduction of BCL2 expression during the development of anorectal development in ARM.

Development of the human bladder and ureterovesical junction

The urinary bladder collects urine from the kidneys and stores it until the appropriate moment for voiding. The trigone and ureterovesical junctions are key to bladder function, by allowing one-way passage of urine into the bladder without obstruction. Embryological development of these structures has been studied in multiple animal models as well as humans. In this report we review the existing literature on bladder development and cellular signalling with particular focus on bladder development in humans. The bladder and ureterovesical junction form primarily during the fourth to eighth weeks of gestation, and arise from the primitive urogenital sinus following subdivision of the cloaca. The bladder develops through mesenchymal-epithelial interactions between the endoderm of the urogenital sinus and mesodermal mesenchyme. Key signalling factors in bladder development include shh, TGF-β, Bmp4, and Fgfr2. A concentration gradient of shh is particularly important in development of bladder musculature, which is vital to bladder function. The ureterovesical junction forms from the interaction between the Wolffian duct and the bladder. The ureteric bud arises from the Wolffian duct and is incorporated into the developing bladder at the trigone. It was previously thought that the trigonal musculature developed primarily from the Wolffian duct, but it has been shown to develop primarily from bladder mesenchyme. Following emergence of the ureters from the Wolffian ducts, extensive epithelial remodelling brings the ureters to their final trigonal positions via vitamin A-induced apoptosis. Perturbation of this process is implicated in clinical obstruction or urine reflux. Congenital malformations include ureteric duplication and bladder exstrophy.

Phenotypic diversity of patients diagnosed with VACTERL association

The combination of vertebral, anal, cardiac, tracheo-esophageal, renal and limb anomalies termed VACTERL association, also referred to as VATER, has been used as a clinical descriptor and more recently, a diagnosis of exclusion, for a specific group of phenotypic manifestations that have been observed to co-occur non-randomly. Though the causes remain elusive and poorly understood in most patients, VACTERL association is thought to be due to defects in early embryogenesis and is likely genetically heterogeneous. We present data on 36 patients diagnosed with VACTERL association in addition to describing the phenotypic diversity of each component feature. Unique cases in our cohort include a patient with a 498.59 kb microdeletion in the 16p11.2 region and another with a 215 kb duplication in the 3p25.2 region. Our findings expand upon the current understanding of VACTERL association and guide future research aimed at determining its etiology.

Maternal drug use and the risk of anorectal malformations: systematic review and meta-analysis

Background

Origin of anorectal malformations (ARM) are considered multifactorial. Several genetic and non-genetic risk factors are discussed in literature. Maternal periconceptional medical drug use as possible risk factor, however, has not been reviewed systematically.

Methods

Studies published between 1977 and April 2017 were reviewed through systematic search in PubMed, ISI Web of Knowledge and Scopus databases. Furthermore, related and cross-referencing publications were reviewed. Pooled odds ratios (95% confidence intervals) were determined to quantify associations of maternal periconceptional use of folic acid, multivitamins, anti-asthma medication (separated in any anti-asthma medication, inhaled corticosteroids and salbutamol), thyroid hormone supplements, psychiatric drugs (separated in antidepressants, any selective serotonin reuptake inhibitors [SSRI], sertraline, citalopram, fluoxetine, paroxetine, hypnotics and benzodiazepine) and aspirin with ARM using meta-analyses.

Results

Thirty-seven studies that reported on the association between maternal periconceptional drug intake and infants born with ARM were included in this review. These were conducted in the United States of America (n = 14), Sweden (n = 6), Hungary (n = 5), Germany (n = 3), the Netherlands (n = 3), Denmark (n = 2), France (n = 2), Norway (n = 1) and the UK (n = 1). However, only few of these studies reported on the same risk factors. Studies were heterogeneous with respect to case numbers, period ingestion of medical drug use, control selection and adjustment for covariates. Consistently increased risks were observed for any anti-asthma medication, and hypnotics and benzodiazepine, but not for folic acid, multivitamins, inhaled corticosteroids, salbutamol, thyroid hormone supplements, antidepressants, any SSRI, sertraline, citalopram, fluoxetine, paroxetine and aspirin. In meta-analyses, pooled odds ratios (95% confidence intervals) for any anti-asthma medication, and hypnotics and benzodiazepine were 1.64 (1.22–2.21), and 2.43 (1.03–5.73), respectively.

Conclusion

Evidence on maternal drug use before conception and during pregnancy as risk factor for ARM from epidemiological studies is still very limited. Nevertheless, the few available studies indicate any anti-asthma medication, and hypnotics and benzodiazepine to be associated with increased risks. Further, ideally large-scale multicenter and register-based studies are needed to clarify the role of maternal drug intake for the development of ARM.

Clinical and risk factor analysis of cloacal defects in the National Birth Defects Prevention Study

Cloacal exstrophy (CE) and persistent cloaca (PC) (alternatively termed urorectal septum malformation sequence [URSMS]), represent two major cloacal defects (CDs). Clinical characteristics and risk factors often are studied for both defects combined, rather than exploring if these defects have different etiologies. We enumerated clinical features for 47 CE and 54 PC (inclusive of URSMS) cases from the National Birth Defects Prevention Study. Thirty-three CE cases were classified as isolated and 14 as multiple (presence of unassociated major defects); respective totals for PC cases were 26 and 28. We compared selected child and maternal characteristics between 11,829 non-malformed controls and CE and PC cases using chi-square or Fisher's exact tests. Compared to controls, CE and PC cases were statistically more likely (p < 0.05) to be preterm; CE cases were more likely to be multiple births. We conducted logistic regression analysis to estimate odds ratios and 95% confidence intervals for any CD, CE, and PC with selected self-reported maternal prepregnancy and periconceptional (one month prior to 3 months following conception) exposures. In crude and adjusted analyses, we observed significant positive associations for any CD, CE, and PC with use of any fertility medication or assisted reproductive technology procedure. Significant positive associations observed only in crude analyses were any CD with maternal obesity or use of progesterone, any CD and CE with any x-ray, and any CD and PC with use of folate antagonist medications. Our findings provide some of the first insights into potential differing etiologies for CE and PC.

Diversities of H-type anorectal malformation: a systematic review on a rare variant of the Krickenbeck classification

Congenital H-type fistula is a rare congenital rectourogenital connection with an external anal opening in a normal or ectopic position. A systematic review was done to study the anatomical types of congenital H-type fistula, embryology, clinical presentation, relative gender distribution, associated anomalies, investigative modalities, and recent advances in treatment of these lesions. A PubMed search included H-type anorectal malformation; H-type anorectal malformations; H-type anorectal; and H-type congenital anorectal that gave 9;43;76;26 abstracts, respectively. Relevant studies and cited articles were studied omitting duplicate search. The reported incidence is 0.1-16 % of all anorectal malformation. The H-type anorectal malformation is 2.5-6 times more common in females and usually associated with a normal anus. In males, the anomaly is usually a variant with an ectopic anus or a perineal fistula. Anatomical types include anovestibular; rectovestibular; rectovaginal fistula in females and rectourethral (bulbar, prostatic, bladder neck) and rectovesical fistula in males. Variants identified include H-type fistula with perineal fistula, perineal groove, H-type sinus, H-type canal, and acquired H-type fistula. This review compiles the available literature over last six decades. Various surgical corrective procedures have been described. The high recurrence decreases with a learning curve and experience.

Perineal raphe with special reference to its extension to the anus: a histological study using human fetuses

The raphe of the human penis and scrotum is considered to develop secondarily after disappearance of the initial midline seam by fusion of the bilateral genital folds. However, the fetal development was still obscure. We examined histological sections of 30 fetuses (17 males and 13 females) at 10–15 weeks. In male fetuses, the scrotum was not yet clearly identified because of no descent of testis. The perineal raphe was thin and wavy at 10 weeks, and it was continuous with and took a direction same as the inferior wall of the closed penile urethra after physiological hypospadias. Depending on growth of the bulbospongiosus muscle and corpus spongiosus penis, the midline intermuscular septum obtained a connection to the subcutaneous wavy raphe and made the latter thick and straight at 12–15 weeks. Notably, the perineal raphe extended posteriorly to attach to the external anal sphincter. In female fetuses, an epithelial fusion occurred along a short distance at the posterior end of the vestibule. However, in front of the external anal sphincter, a large midline mesenchymal tissue from the urorectal septum did not contain a raphe-like structure. Moreover, since the bilateral bulbospongiosus muscles were separated widely by the vestibule, they did not provide a midline septum. Fetal development of the perineal raphe was accelerated by reinforcement from the muscular septum. In contrast, without such a muscular support, the female raphe could not maintain its growth even if the seed appeared at the posterior end of the vestibule.

Fetal growth of the anal sinus and sphincters, especially in relation to anal anomalies

PURPOSE AND METHODS

The anal sinuses, small furrows above the pectinate line, sometimes form perianal abscesses in adults. We examined the pattern of fetal growth of the anal sinus and sphincters using 22 mid-term (8-18 weeks) and 6 late-stage (30-38 weeks) fetuses.

RESULTS

In mid-term fetuses, the external and internal sphincters gradually increased in thickness, depending on specimen size (from 0.2 to 1.5 mm), whereas the anteroposterior diameter of the anal canal at the epithelial junction was relatively stable (0.5-1.0 mm) irrespective of specimen size. Anal canal diameter increased less than twofold between mid-term and late-stage fetuses, from 0.5-1.0 to almost 2 mm, whereas sphincter thickness increased over tenfold, from 0.2-1.5 to almost 3.5 mm. The anal sinus often showed balloon-like enlargement when the sphincter muscle bundles were tightly packed in mid-term, but not in late-stage fetuses.

CONCLUSIONS

Large concentric mechanical stress from the sphincters in late-stage fetuses apparently prevented the anal sinus from expanding in a balloon-like manner. Conversely, to avoid anal stenosis, the growing sinuses maintained a luminal space of the anal canal in response to stress from rapidly growing sphincters. The inferiorly extending sinus usually provided temporal double canals separated by a thick column. In the presence of double lumens, anal canal duplication is likely to develop without any abnormalities of the anal epithelium and sphincters.

Parental risk factors of anorectal malformations: Analysis with a regional population-based control group

BACKGROUND

Adequate evidence on environmental risk factors for anorectal malformations (ARMs) is very limited. We assessed maternal body weight and several prenatal exposures of the parents to tobacco, pregestational diabetes, chronic cardiovascular and respiratory diseases, periconceptional folic acid and multivitamin intake.

METHODS

Data from the German Network for Congenital Uro-REctal malformations (CURE-Net) were compared with data from the Malformation Monitoring Centre Saxony-Anhalt of the Otto-von-Guericke University in Magdeburg, Germany. Controls were matched to cases by gender and birth year of the child. Crude and adjusted odds ratios (95% confidence intervals) were calculated for potential risk factors using multivariable logistic regression.

RESULTS

In total, 158 ARM patients and 474 healthy infants born between 1993 and 2008 in Germany were included. Maternal age at birth of ARM cases and birth plurality were significantly higher and gestational age and weight significantly lower compared with controls (p < 0.0001). We observed significantly increased risks for ARMs associated with maternal smoking before conception and the first trimester of pregnancy (odds ratio = 2.23, 95% confidence interval 1.04-4.79, p = 0.039) and maternal chronic respiratory diseases (odds ratio = 29.25, 95% confidence interval 8.22-104.14, p < 0.0001). No statistically significant increased risk or protective effect was found for the other investigated factors.

CONCLUSION

This study suggests an association between the occurrence of ARMs in the offspring and periconceptional maternal smoking as well as maternal chronic respiratory diseases. In addition, there might be a sign of an association for maternal diabetes, although not statistically significant. It can be assumed that the power is far too low to provide reliable estimates.

Clarification of mammalian cloacal morphogenesis using high-resolution episcopic microscopy

The developmental process through which the cloaca transforms from one hollow structure to two separated urinary and digestive outlets remains controversial and speculative. Here, we use high-resolution episcopic microscopy to examine a comprehensive series of normal and mutant mouse cloaca in which the detailed 3-dimensional (3-D) morphological features are illuminated throughout the development. We provide evidence that the dorsal peri-cloacal mesenchyme (dPCM) remains stationary while other surrounding tissues grow towards it. This causes dramatic changes of spatial relationship among caudal structures and morphological transformation of the cloaca. The 3-D characterizations of Dkk1 mutants reveal a hyperplastic defect of dPCM, which leads to a significant anterior shift of the caudal boundary of the cloaca, premature occlusion of the cloaca and, imperforate anus phenotype. Conversely, Shh knockout causes a severe hypoplastic defect of cloaca mesenchyme including dPCM and persistent cloaca. Collectively, these findings suggest that formation of the dPCM is critical for cloacal morphogenesis and furthermore, growth and movement of the mesenchymal tissues towards the dPCM lead to the cloaca occlusion and separation of the urinary and digestive outlets.

An illustrated anatomical ontology of the developing mouse lower urogenital tract

Malformation of the urogenital tract represents a considerable paediatric burden, with many defects affecting the lower urinary tract (LUT), genital tubercle and associated structures. Understanding the molecular basis of such defects frequently draws on murine models. However, human anatomical terms do not always superimpose on the mouse, and the lack of accurate and standardised nomenclature is hampering the utility of such animal models. We previously developed an anatomical ontology for the murine urogenital system. Here, we present a comprehensive update of this ontology pertaining to mouse LUT, genital tubercle and associated reproductive structures (E10.5 to adult). Ontology changes were based on recently published insights into the cellular and gross anatomy of these structures, and on new analyses of epithelial cell types present in the pelvic urethra and regions of the bladder. Ontology changes include new structures, tissue layers and cell types within the LUT, external genitalia and lower reproductive structures. Representative illustrations, detailed text descriptions and molecular markers that selectively label muscle, nerves/ganglia and epithelia of the lower urogenital system are also presented. The revised ontology will be an important tool for researchers studying urogenital development/malformation in mouse models and will improve our capacity to appropriately interpret these with respect to the human situation.

Defining the molecular pathologies in cloaca malformation: similarities between mouse and human

Anorectal malformations are congenital anomalies that form a spectrum of disorders, from the most benign type with excellent functional prognosis, to very complex, such as cloaca malformation in females in which the rectum, vagina and urethra fail to develop separately and instead drain via a single common channel into the perineum. The severity of this phenotype suggests that the defect occurs in the early stages of embryonic development of the organs derived from the cloaca. Owing to the inability to directly investigate human embryonic cloaca development, current research has relied on the use of mouse models of anorectal malformations. However, even studies of mouse embryos lack analysis of the earliest stages of cloaca patterning and morphogenesis. Here we compared human and mouse cloaca development and retrospectively identified that early mis-patterning of the embryonic cloaca might underlie the most severe forms of anorectal malformation in humans. In mouse, we identified that defective sonic hedgehog (Shh) signaling results in early dorsal-ventral epithelial abnormalities prior to the reported defects in septation. This is manifested by the absence of Sox2 and aberrant expression of keratins in the embryonic cloaca of Shh knockout mice. Shh knockout embryos additionally develop a hypervascular stroma, which is defective in BMP signaling. These epithelial and stromal defects persist later, creating an indeterminate epithelium with molecular alterations in the common channel. We then used these animals to perform a broad comparison with patients with mild-to-severe forms of anorectal malformations including cloaca malformation. We found striking parallels with the Shh mouse model, including nearly identical defective molecular identity of the epithelium and surrounding stroma. Our work strongly suggests that early embryonic cloacal epithelial differentiation defects might be the underlying cause of severe forms of anorectal malformations in humans. Moreover, deranged Shh and BMP signaling is correlated with severe anorectal malformations in both mouse and humans.

Anal duplication in a one-year-old girl

We report a case of a patient with anal duplication discovered incidentally at 1 year of age. Pre-operative evaluation excluded any complications or associated anomalies. She underwent surgical excision with an excellent outcome.

Anorectal Malformations: Finding the Pathway out of the Labyrinth

Anorectal malformations (ARMs) are a complex group of congenital anomalies involving the distal anus and rectum, as well as the urinary and genital tracts in a significant number of cases. Most ARMs result from abnormal development of the urorectal septum in early fetal life. In most cases, the anus is not perforated and the distal enteric component ends blindly (atresia) or as a fistula into the urinary tract, genital tract, or perineum. ARMs are also present in a great number of syndromes and associations of congenital anomalies. The classification of ARMs is mainly based on the position of the rectal pouch relative to the puborectal sling, the presence or absence of fistulas, and the types and locations of the fistulas. All of this information is crucial in determining the most appropriate surgical approach for each case. Imaging studies play a key role in evaluation and classification of ARMs. In neonates, clinical and radiologic examinations in the first 3 days of life help determine the type of ARM and the need for early colostomy. In older children, preoperative pelvic magnetic resonance imaging is the most efficient diagnostic method for evaluating the size, morphology, and grade of development of the sphincteric musculature.

Development of the human tail bud and splanchnic mesenchyme

The purpose of this paper was to shed some light on anorectal development from a viewpoint of the tail bud and splanchnic mesenchyme for better understanding of the morphogenesis of the human anorectum. Human embryos ranging from Carnegie stage 11 to 23 (CS 11 to 23) were adopted in this study. Seventeen embryos preserved at the Congenital Anomaly Research Center of Kyoto University Graduate School of Medicine were histologically examined. The cloaca, extending caudally to the hindgut, was dramatically enlarged, particularly both its dorsal portion and membrane, that is, the cloacal membrane resulting from the development of the tailgut derived from the tail bud. The splanchnic mesenchyme surrounding the hindgut was spread out in the direction of the urorectal septum ventrally, suggesting that it participated in the formation of the septum. No fusion of the urorectal septum and the cloacal membrane was found. The splanchnic mesenchyme proliferated and developed into smooth muscle (circular and longitudinal) layers from cranial to caudal along the hindgut. The tail bud seems to cause both the adequate dilation of the dorsal cloaca and the elongation of the cloacal membrane; its dorsal portion in particular will be necessary for normal anorectal development. The splanchnic mesenchyme developed and descended toward the pectinate line and formed the internal sphincter muscle at the terminal bowel.

Classical cloacal exstrophy with intravesical phallus

Penile abnormalities such as epispadias, diphallia, asymmetry, and aphallia have been reported with cloacal exstrophy. The presence of intravesical phallus with cloacal exstrophy is presented with a review of literature.

A continent urinary diversion in a female with agenesis of the bladder: a 5-year follow-up

There are few case reports of bladder agenesis. The outcome of the patients differs and depends on the associated malformations. Different urinary diversions are described to save renal function. Most of the surviving patients with bladder agenesis have undergone incontinent urinary diversions as primary treatment. We describe the case of a female infant with agenesis of the bladder that arrived in our institution after several septic episodes. Treatment of choice was a continent pouch with an appendicovesicostomy. We state that even in young children, a primary continent urinary diversion can be performed with excellent long-term outcome.

Cloacal exstrophy: an epidemiologic study from the International Clearinghouse for Birth Defects Surveillance and Research

Cloacal exstrophy presents as a complex abdominal wall defect thought to result from a mesodermal abnormality. Anatomically, its main components are Omphalocele, bladder Exstrophy and Imperforate anus. Other associated malformations include renal malformations and Spine defects (OEIS complex). Historically, the prevalence ranges from 1 in 200,000 to 400,000 births, with higher rates in females. Cloacal exstrophy is likely etiologically heterogeneous as suggested by its recurrence in families and occurrence in monozygotic twins. The defect has been described in infants with limb-body wall, with trisomy 18, and in one pregnancy exposed to Dilantin and diazepam. Due to its rarity, the use of a nonspecific diagnostic code for case identification, and lack of validation of the clinical findings, cloacal exstrophy remains an epidemiologic challenge. The purpose of this study was to describe the prevalence, associated anomalies and maternal characteristics among infants born with cloacal exstrophy. We used data from the International Clearinghouse for Birth Defects Surveillance and Research submitted from 18 birth defect surveillance programs representing 24 countries. Cases were clinically evaluated locally and reviewed centrally by two authors. Cases of persistent cloaca were excluded. A total of 186 cases of cloacal exstrophy were identified. Overall prevalence was 1 in 131,579 births: ranging from 1 in 44,444 births in Wales to 1 in 269,464 births in South America. Live birth prevalence was 1 in 184,195 births. Prevalence ratios did not vary by maternal age. Forty-two (22.6%) cases met the criteria for the OEIS complex, whereas 60 (32.3%) were classified as OEI and 18 (9.7%) as EIS (one with suspected VATER (0.5%)). Other findings included two cases with trisomy 13 (one without a karyotype confirmation), one with mosaic trisomy 12 (0.5%), one with mosaic 45,X (0.5%) and one classified as having amnion band sequence (0.5%). Twenty-seven (14.5%) infants had other anomalies unrelated to cloacal exstrophy. Cloacal exstrophy is a rare anomaly with variability in prevalence by geographic location. The proportion of cases classified as OEIS complex was lower in this study than previously reported. Among all cases, 54.8% were reported to have an omphalocele.

Management of H-type rectovestibular and rectovaginal fistulas

INTRODUCTION

H-type rectovestibular or rectovaginal fistulas are rare entities in the spectrum of anorectal malformations seen in North America. Management options described in the literature have included perineal repair, anterior perineal anorectoplasty, vestibuloanal pull-through, and limited or formal posterior sagittal anorectoplasty, with a reported recurrence rate of 5% to 30%. We describe our approach and outcome in the management of these patients.

METHODS

In a series of 1170 females with anorectal malformation, we cared for 8 patients who had an H-type rectovestibular or rectovaginal fistula and reviewed their clinical presentation, diagnosis, operative technique, and postoperative course.

RESULTS

The patients' presenting symptoms included passage of stool per vagina (6), constipation (3), labial abscess (1), and recurrent urinary tract infection (1). There was associated anorectal stenosis in 3 patients. The remaining 5 patients had normal anal openings. Endoscopy was not helpful in locating the fistulas, but the fistulas were all demonstrated on direct inspection under anesthesia. The fistula was located in the vestibule (4), vagina (3), or labia (1). One patient had an associated presacral mass. Two patients had been operated on twice previously using a perineal repair and a protective colostomy and presented with third recurrences. In 5 cases, a posterior sagittal approach was used, placing sutures circumferentially around the fistulous opening on the rectal side, ligating the fistula, and pulling down a normal segment of rectum to be placed in front of the repaired vaginal wall. In our last 3 cases, we performed a transanal mobilization of the anterior rectal wall, leaving the perineal body intact. After our repairs, the patients have been followed up for 3 months to 15 years with a median of 15 months, and we have seen no recurrences.

CONCLUSIONS

In addition to vaginal passage of stool, an H-type fistula should be suspected when there is a labial abscess in an infant, and an associated anal stenosis or presacral mass must be checked for. Direct inspection is the key, with a careful look in the vestibule, because endoscopy may miss the fistula. The essential technical point for repair is to get healthy anterior rectal wall to cover the area of fistula on the posterior vagina. A transanal approach, leaving the perineal body intact, is an excellent option for this repair.

Analysis of genitourinary anomalies in patients with VACTERL (Vertebral anomalies, Anal atresia, Cardiac malformations, Tracheo-Esophageal fistula, Renal anomalies, Limb abnormalities) association

The goal of this study was to describe a novel pattern of genitourinary (GU) anomalies in VACTERL association,which involves congenital anomalies affecting the vertebrae,anus, heart, trachea and esophagus, kidneys, and limbs.We collected clinical data on 105 patients diagnosed with VACTERL association and analyzed a subset of 89 patients who met more stringent inclusion criteria. Twenty-one percent of patients have GU anomalies, which are more severe (but not more frequent) in females. Anomalies were noted in patients without malformations affecting the renal, lower vertebral, or lower gastrointestinal systems. There should be a high index of suspicion for the presence of GU anomalies even in patients who do not have spatially similar malformations.

Parental risk factors and anorectal malformations: systematic review and meta-analysis

BACKGROUND

Anorectal malformations (ARM) are rare forms of congenital uro-rectal anomalies with largely unknown causes. Besides genetic factors, prenatal exposures of the parents to nicotine, alcohol, caffeine, illicit drugs, occupational hazards, overweight/obesity and diabetes mellitus are suspected as environmental risk factors.

METHODS

Relevant studies published until August 2010 were identified through systematic search in PubMed, EMBASE, ISI Web of Knowledge and the Cochrane Library databases. Furthermore, related and cross-referencing publications were reviewed. Pooled odds ratios (95% confidence intervals) were determined to quantify associations of maternal and paternal smoking, maternal alcohol consumption, underweight (body mass index [BMI] < 18.5), overweight (BMI 25-29.9), obesity (BMI ≥30) and maternal diabetes mellitus with ARM using meta-analyses.

RESULTS

22 studies that reported on the association between prenatal environmental risk factors and infants born with ARM were included in this review. These were conducted in the United States of America (n = 12), Spain (n = 2), Sweden (n = 2), the Netherlands (n = 2), Japan (n = 1), France (n = 1), Germany (n = 1) and Hungary (n = 1). However, only few of these studies reported on the same risk factors. Studies were heterogeneous with respect to case numbers, control types and adjustment for covariates. Consistently increased risks were observed for paternal smoking and maternal overweight, obesity and diabetes, but not for maternal smoking and alcohol consumption. In meta-analyses, pooled odds ratios (95% confidence intervals) for paternal smoking, maternal overweight, obesity, pre-gestational and gestational diabetes were 1.53 (1.04-2.26), 1.25 (1.07-1.47), 1.64 (1.35-2.00), 4.51 (2.55-7.97) and 1.81 (1.23-2.65), respectively.

CONCLUSION

Evidence on risk factors for ARM from epidemiological studies is still very limited. Nevertheless, the few available studies indicate paternal smoking and maternal overweight, obesity and diabetes to be associated with increased risks. Further, ideally large-scale multicentre and register-based studies are needed to clarify the role of key risk factors for the development of ARM.

The development of satellite cells and their niche in striated muscle complex of anorectal malformations rat embryos

BACKGROUND

It has been demonstrated that different degrees of pelvic floor muscle (PFM) maldevelop in anorectal malformations (ARMs); yet the development of satellite cells, the myogenic stem cells responsible for muscle growth, repair, and maintenance remains elusive during the embryogenesis of PFM. Striated muscle complex (SMC) is one of the most important components of PFM. The objective of this study was to observe the development pattern of satellite cells and their niche of SMC and investigate its possible role in PFM dysplasia in ARMs.

METHODS

Immunohistochemistry, cell culture, transmission electron microscopy (TEM), real-time quantitative PCR, and Western blot were performed to trace the dynamic development pattern of satellite cells during the morphogenesis of PFM in ethylenethiourea (ETU)-induced ARMs rat embryos.

RESULTS

In ARMs rat embryos, earlier presentation and higher number of Pax7-expressing cell were observed in SMC. The expression of Pax7 and vimentin were up-regulated, while the expression of myogenin, vWF, and neurofilament were down-regulated. Ultrastructure analysis of SMC was characterized by increased amount of nuclear heterochromatin of satellite cell nuclei, thickened basal lamina, widened gap between satellite cell and myofiber, and disarrangement of muscle fibers. The satellite cells demonstrated abnormal differentiation after they were isolated and cultured in vitro.

CONCLUSIONS

Our results suggest that premature origination of satellite cell from myogenic progenitor or precursor may result in the depletion of myogenic precursor and cessation of muscle growth; intrinsic defect in satellite cell structure, and extrinsic impairment of microenvironment compromised the myogenic competence of satellite cell, which might contribute substantially to the hypoplastic SMC in ARMs.

Normal development of hindgut and anorectum in human embryo

PURPOSE

The aim of the present analysis is to examine the morphological changes, the spatiotemporal distribution of apoptosis/proliferation in the human embryonic anorectum, to reveal the normal development of human anorectum, and investigate the possible roles of apoptosis/proliferation during anorectal development.

MATERIALS AND METHODS

The embryos were sectioned serially and sagittally, stained with hematoxylin and eosin (H & E) between the third and eighth week of gestation, TdT-mediated dUTP-digoxigenin nick end-labeling (TUNEL) and proliferative cell-specific nuclear antigen (PCNA) immunohistochemical staining from the sixth to the eighth week.

RESULTS

From the fourth to the seventh week, with the growth of the mesenchyme around the cloaca, the cloaca was remolded, subsequently, the cloacal membrane (CM) moved perpendicularly then horizontally. The dorsal cloaca gradually descended to the tail groove, the urorectal septum (URS) and the CM approximated; however, the fusion of URS with the dorsal CM was never observed. During the eighth week, the URS shifted ventrally and finally fused with the ventral CM. Moreover, from the sixth to the eighth week, the apoptotic cells were concentrated in the CM, the mesenchyme of terminal rectum, and the dorsal rectum. Meanwhile, the proliferative cells could be observed in the ventral mesenchyme around the cloaca, the CM, the fused tissue between the URS, and the ventral CM.

CONCLUSIONS

During the development of human anorectum, it was intriguing to reveal that the URS never fused with the dorsal CM before dorsal CM disintegration, the normal anorectal development may depend on the dorsal cloaca and the dorsal CM; furthermore, the distribution of apoptosis and proliferation in the anorectum and ventral cloacal mesenchyme played a pivotal role in the formation of the anorectum.

Perineal groove-a case report

The perineal groove is a rare congenital anomaly of the perineum. We present a case of this uncommon condition that had been misinterpreted as irritant dermatitis following treatment for diaper rash. To our knowledge this is the first report of this condition is the dermatology literature.

False positive reactivity of a substance P-antibody in the ectodermal/epithelial plug of the nose, ear, eye and perineum of the human and mouse fetuses

Epithelial/ectodermal plug formation in the developing nose, ear, and eye regions is followed by canalization/recanalization mediated by cell death. However, the mechanism is not well understood. Recently, substance P (SP)-mediated cell death, rather than cell apoptosis, has been reported in neuronal and non-neuronal cells. Horizontal paraffin sections of 5 human fetuses at 15-16 weeks of gestation were used to examine the entire area of the nose, ear, eye and perineum with immunohistochemistry for SP and its receptor neurokinin-1 (NK-1), and protein gene product (PGP) 9.5 and S100 protein to identify whether the positive cells had neural origins. The deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) method was also conducted to identify apoptosis. Four SP antibodies were commercially obtained and compared the results. In addition, using the same antibodies for SP, those results were compared with fetal mouse heads (E14-17). Substance P immunoreactivity of one of the 4 antibodies (sc9758) was clearly found in the nasal plug, the epithelium of the anterior nasal cavity, the entire excretory tear duct, the marginal palpebral conjunctiva, the auditory meatal plug, the parotid duct, the external urethral orifice and, the preputial lamella along the future prepuce. Immunoreactivity was usually seen in enlarged round cells in humans. In fetal mouse heads, in spite of negative reaction in all these sites, the midline epithelial seam at the palate fusion and the oral epithelium especially at and near the tooth germ specifically reacted with the sc9758. Nevertheless, the other 3 antibodies did not react at any of those sites both in human and mouse fetuses. NK-1 receptor-positive cells were seen in the nose and meatal plugs and preputial lamella, but not in the tear duct. S100 protein, PGP 9.5, and TUNEL method all demonstrated negative reactivity at any sc9758-positive sites. Consequently, the present immunoreactivity of the sc9758 antibody seemed to be false positive, but it was likely to react with a specific substance in the epithelial or ectodermal cell because of the clearly restricted staining. Which substance it crossed remains unknown.

Anal canal duplication: experience at a single institution and literature review

PURPOSE

Anal canal duplication (ACD) is an extremely rare congenital intestinal anomaly. There are not many reports in the English literature, with just a few from each institution. The aim of this study was to describe the clinical characteristics, surgical treatment, and outcome of ACD in pediatric cases at a single institution.

METHOD

The medical records of ACD patients we treated from 1988 to 2009 were reviewed retrospectively.

RESULTS

There were ten cases, all females. Nine were asymptomatic without any history of perianal infection, identified only incidentally at routine check-up although one case had severe periproctal abscess. Mean age at diagnosis was 6 months (range 0-47 months). Concurrent pathology present were meningocele and presacral mass in one, presacral mass in one, and renal hypoplasia in one. In all cases, an extraneous perianal orifice opening in the midline posterior to the native anus was present, but in one case it was only identified at surgery because it had closed secondary to severe inflammation preoperatively. All had preoperative radiologic investigations, such as magnetic resonance imaging (MRI), barium contrast studies, and fistulography. Mean age at surgery was 14 months (range 1-48 months). All underwent surgical removal of the anal canal duplication, eight through a perineal approach and two through a posterior sagittal approach, depending on the length of the duplicated anal canal and the presence of concurrent anomalies. Histopathology of the excised anal canals showed squamous epithelium in all cases. The postoperative course was uneventful in all cases and all are well without complications at mean follow-up of 9.1 years (range 5-19 years).

CONCLUSION

This is the largest series of ACD at a single institution reported to date. For the clinician faced with an extraneous perianal orifice located posteriorly in the midline with respect to the native anus, ACD should be suspected. The treatment of choice in children is complete excision (perineal/posterior sagittal approach), even if asymptomatic. Morbidity is minimal, and outcome is excellent.

Anal canal duplication

INTRODUCTION

Anal canal duplication (ACD) is an extremely rare congenital intestinal anomaly. ACD is defined as a second anal orifice located posterior to the true anus ending blindly without connection to the rectum. Usually, there are no other accompanying hindgut pathologies. Patients are often asymptomatic and apply to clinics with their parent's attention. CASE 1: A 9-month-old girl was referred to our clinic because of a second orifice posterior to the true anus. On the physical examination, there was a 3 mm in diameter orifice, about 0.5 cm behind the anus, at 6 o'clock direction on the lithotomy position. Duplicated lumen was checked with a metal catheter; it was about 2 cm in length ending blindly without connection to the rectum. A prediagnosis of ACD was made and the patient was operated. Duplicated segment was excised totally. Postoperative course was uneventful. CASE 2: One-year-old girl was referred to our clinic because of the same complaint. On the physical examination, there was a 2 mm in diameter orifice, about 0.3 cm behind the anus, at 6 o'clock direction on lithotomy position. Duplicated lumen was checked with a metal catheter; it was about 1.5 cm in length ending blindly without connection to the rectum.

CONCLUSION

ACD is a rare congenital intestinal anomaly located posterior to the anus. It can be confused with other types of anorectal pathologies, such as hemorrhoids, fistula-in-ano, and perianal abscess at the time of diagnosis. Although ACD is often asymptomatic, it should be removed surgically because of the risk of inflammatory complications and colloidal cancer.

Imperforate anus is a rare associated finding in blepharocheilodontic syndrome

Blepharocheilodontic (BCD) syndrome is a rare autosomal-dominant condition that is characterized by lower eyelid ectropion, upper eyelid distichiasis, euryblepharon, bilateral cleft lip and palate, and conical teeth. It exhibits considerable phenotypic variability among affected individuals. An additional rare associated manifestation is imperforate a.u. (IA), which has been reported in three cases [Guyuron et al. (1995); J Craniofac Surg 6:392-394; Gorlin et al. (1996); Am J Med Genet 65:109-112; da Silva Lopes et al. (2003); Am J Med Genet Part A 121A:266-270]. Here we report on a family with BCD that includes IA, confirming that anorectal anomalies are a part of BCD syndrome.

Multiphasic and tissue-specific roles of sonic hedgehog in cloacal septation and external genitalia development

Malformations of the external genitalia are among the most common congenital anomalies in humans. The urogenital and anorectal sinuses develop from the embryonic cloaca, and the penis and clitoris develop from the genital tubercle. Within the genital tubercle, the endodermally derived urethral epithelium functions as an organizer and expresses sonic hedgehog (Shh). Shh knockout mice lack external genitalia and have a persistent cloaca. This identified an early requirement for Shh, but precluded analysis of its later role in the genital tubercle. We conducted temporally controlled deletions of Shh and report that Shh is required continuously through the onset of sexual differentiation. Shh function is divisible into two temporal phases; an anogenital phase, during which Shh regulates outgrowth and patterning of the genital tubercle and septation of the cloaca, and a later external genital phase, during which Shh regulates urethral tube closure. Disruption of Shh function during the anogenital phase causes coordinated anorectal and genitourinary malformations, whereas inactivation during the external genital phase causes hypospadias. Shh directs cloacal septation by promoting cell proliferation in adjacent urorectal septum mesenchyme. Additionally, conditional inactivation of smoothened in the genital ectoderm and cloacal/urethral endoderm shows that the ectoderm is a direct target of Shh and is required for urethral tube closure, highlighting a novel role for genital ectoderm in urethragenesis. Identification of the stages during which disruption of Shh results in either isolated or coordinated malformations of anorectal and external genital organs provides a new tool for investigating the etiology of anogenital malformations in humans.

Expression of EphB2 in the development of anorectal malformations in fetal rats

PURPOSE

The receptor tyrosine kinase of the Eph family is a large group of highly conserved molecules that function in diverse intercellular recognition events. It has been reported that EphB2 is related to caudal remodeling events. The aim of this study is to investigate EphB2 expression in anorectal development in normal and rat embryos with anorectal malformations (ARMs) and attempt to define its role in anorectal morphogenesis.

METHODS

The ethylenethiourea (ETU) rat model of the ARMs was used in this study. Immunohistochemical analyses and real time quantitative polymerase chain reaction (PCR) were carried out to investigate EphB2 protein localizations and messenger RNA (mRNA) expression levels. (1) Rat embryos with ARMs were obtained by treating pregnant rats (n = 24) with administration of ETU on gestation day (Gd) 10. Normal rat embryos (n = 111) and embryos treated by ETU without ARMs (n = 90) were the control groups, and embryos with ARMs (n = 108) from Gd13 to Gd16 were divided according to the sections taken from specimens. (2) Embryos were sequentially sectioned in the sagittal and transversal planes before staining with a specific antibody to EphB2. Spatiotemporal study was carried out on EphB2 expression. (3) Individual frozen sections were used to manually microdissect the cloaca and anorectal specimens for total RNA extraction. EphB2 expression was evaluated by real time quantitative PCR.

RESULTS

On the immunologic labeling study, EphB2 expression was confined to the cloaca in control groups, whereas EphB2 expression was mainly located at the urorectal septum (URS) and cloacal membrane on Gd13 and Gd14. The increased positive expression was observed in the fused tissue of the URS and cloacal membrane on Gd15. On Gd16, the anal membrane broke down, and the rectum was able to be in contact with the anus, and EphB2 expression was then noted in mucous membrane of rectum. EphB2 expression was seen in the cloacal and anorectal tissues of embryos with ARMs. By integrated optical density (IOD) measurement, IOD value of EphB2 protein was significantly lower in the ARM group than that in the control groups on Gd13 to Gd16 (P < .05), respectively. As shown by real time quantitative PCR, EphB2 expression was detected in 3 groups. EphB2 mRNA level increased on Gd13 to Gd16 but gradually decreased after Gd16. The expression level of EphB2 mRNA in the ARM embryos was lower on Gd13 to Gd16 than that in control groups (P < .05).

CONCLUSIONS

EphB2 expression decreased in the ARM embryos and was confined to URS and cloaca, whereas it was higher in control group. Our data thus indicated that EphB2 molecules possibly contributed to the anorectal morphogenesis and the decreased expression of EphB2 might be related to the development of ARMs.

Urorectal septum malformation sequence: a report of seven cases

Urorectal septum malformation (URSM) sequence is an extremely uncommon anomaly. We report herein seven cases of URSM sequence that were identified after reviewing all autopsies conducted at our hospital over a period of 26 years (1981-2006). The URSM spectrum includes partial and full URSM sequences. Absent perineal and anal openings with ambiguous genitalia are included under 'full URSM sequence', and a single perineal or anal opening draining a common cloaca with an imperforate anus is called 'partial URSM sequence'. Of our seven cases of URSM, three were full URSM sequence and four were partial URSM sequence. Associated renal anomalies were found in all of the cases. Three cases had unilateral renal agenesis and one each had bilateral renal agenesis and bilateral renal dysplasia, respectively. The remaining two cases had unilateral renal agenesis with contralateral kidney showing features of cystic dysplastic kidney and renal hypoplasia, respectively. Congenital anomalies involving other organs were also found in some of the cases. The longest survival period in our series was 10 days, in accordance with the short survival period usually associated with URSM. Five of the patients were females, one was male, and the sex of one neonate could not be ascertained. One of the neonates was from a twin pregnancy; the other twin was normal.

Cell lineage analysis demonstrates an endodermal origin of the distal urethra and perineum

Congenital malformations of anorectal and genitourinary (collectively, anogenital) organs occur at a high frequency in humans, however the lineage of cells that gives rise to anogenital organs remains poorly understood. The penile urethra has been reported to develop from two cell populations, with the proximal urethra developing from endoderm and the distal urethra forming from an apical ectodermal invagination, however this has never been tested by direct analysis of cell lineage. During gut development, endodermal cells express Sonic hedgehog (Shh), which is required for normal patterning of digestive and genitourinary organs. We have taken advantage of the properties of Shh expression to genetically label and follow the fate of posterior gut endoderm during anogenital development. We report that the entire urethra, including the distal (glandar) region, is derived from endoderm. Cloacal endoderm also gives rise to the epithelial linings of the bladder, rectum and anterior region of the anus. Surprisingly, the lineage map also revealed an endodermal origin of the perineum, which is the first demonstration that endoderm differentiates into skin. In addition, we fate mapped genital tubercle ectoderm and show that it makes no detectable contribution to the urethra. In males, formation of the urethral tube involves septation of the urethral plate by continued growth of the urorectal septum. Analysis of cell lineage following disruption of androgen signaling revealed that the urethral plate of flutamide-treated males does not undergo this septation event. Instead, urethral plate cells persist to the ventral margin of the tubercle, mimicking the pattern seen in females. Based on these spatial and temporal fate maps, we present a new model for anogenital development and suggest that disruptions at specific developmental time points can account for the association between anorectal and genitourinary defects.