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AIM A modified repair technique for traumatic cloaca caused by obstetric anal sphincter injury was evaluated, and its feasibility and functional outcome were investigated. METHODS A retrospective review of 23 consecutively enrolled patients diagnosed with traumatic cloaca who underwent the modified repair technique between September 2010 and August 2018 was performed. Demographic, clinical feature, operative and follow-up data were recorded. RESULTS The patients diagnosed with traumatic cloaca who underwent surgical repair after obstetric anal sphincter injury had a median time from obstetric injury of 24 (12-35) years. The median preoperative Wexner faecal incontinence score was 16 (14-17). The postoperative hospital stay was 6 (6-7) days. The median postoperative Wexner faecal incontinence score decreased to 2 (2-3). The anal resting pressure increased from 9.00 (5.25-11.50) mmHg to 56.00 (55.00-65.75) mmHg (P

We present a case of a girl with an extremely rare, posterior type of persistent cloaca, which was associated with other abnormalities, including an undeveloped vulva and vagina, agenesis of the right kidney, secondary obstructive megaureter, unicornate uterus, persisted tailgut, sacral bone hypoplasia, and pubic symphysis hypertrophy. An operative approach was as follows: (i) colostomy and ureterocutaneostomy; (ii) creation of an ileal conduit with antirefluxing uretero-ileal anastomosis, and then creation of a continent catheterizable ileal reservoir; (iii) anastomosis of sigmoid colon to rectal stump; and (iv) vaginal and external genital reconstruction. Because of abnormal anatomical conditions where the uterus was situated adjacent to the open, incompetent bladder neck, we decided to create a vagina using the bladder wall instead of the bowel segment.

We describe a new sonographic sign for the detection of anal atresia in the early midtrimester on transvaginal sonography. In six cases of fetal anal atresia, the finding of a transient, distended, and right-sided sigmoid colon was observed at 13-16 weeks' gestation. Three cases have undergone pregnancy termination due to multiple anomalies. In the other three, the colonic distension resolved by 19 weeks' gestation. In two of these, the finding was isolated, and no other anomalies were detected. In all six cases, anal atresia or cloaca was confirmed on postabortal autopsy or after delivery. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:160-162, 2017.

The structures of the female reproductive system (ovary, oviduct and cloaca) of Ichthyophis supachaii were investigated by dissection, histology and light microscopy. Paired, elongated, sac-like ovaries are parallel to the gut and fat bodies. Follicle stages include germinal nests of oogonia and primary oocytes, early and late previtellogenic follicles, early and late vitellogenic follicles and atretic follicles. Germinal nests of oogonia comprise oogonia and prefollicular cells. Nests of primary oocytes contain clusters of synchronously developing primary oocytes enclosed by connective tissue. Primary oocytes are associated with follicular cells. Previtellogenic follicles initially form the vitelline envelope, theca cell layers and patches of ooplasmic glycoproteins. Vitellogenic follicles contain heterogeneously sized spherical yolk granules. Atresia is present in several stages of developing follicles. The oviduct is divided into the anterior, middle and posterior parts. All oviductal parts are lined by non-ciliated epithelium. A small number of mucous cells are present in the middle part. The cloaca of female I. supachaii is divided into the anterior and posterior chambers. The anterior chamber is lined by glandular stratified columnar epithelium, while the posterior chamber has stratified cuboidal epithelium with less mucus production. Our results contribute to useful information on the reproductive biology of caecilians.

Ultrasonic techniques allow for noninvasive detection of prenatal abnormalities. The management of a delivered baby and the subsequent course are strongly influenced by intrauterine detection. A case of exstrophy of the cloaca with ectopia cordis was prenatally diagnosed by ultrasonography. Ectopia cordis and exstrophy of the cloaca are both rare anomalies. Ectopia cordis can be detected when the heart is outside the thoracic cage and a small thorax is seen on the ultrasonography. Exstrophy of the cloaca can be suspected when omphalocele and meningomyelocele are present, the urinary bladder is absent, and internal and/or external genitalia are abnormal by ultrasonography. Careful and repeated ultrasound study will confirm the combined anomalies of ectopia cordis and exstrophy of the cloaca.

The urorectal septum malformation sequence (URSMS) is characterized by severe abnormalities of the urorectal septum (URS) and urogenital organs. The primary defect in this condition appears to be a deficiency in caudal mesoderm leading to the malformation of the URS and other structures in the pelvic region. Recent clinical reports discuss prental findings of URSMS [Lubusky et al. (2006); Prenatal Diagnosis 26: 345-349]. However, here we present a case of URSMS with prenatal findings not previously described, review the literature on URSMS, and summarize current embryological understanding of the pathology seen in hindgut development. The unique prenatal finding in the patient was an abdominally located cystic mass that was first seen at 18 weeks of gestation. Over the next 6 weeks, the mass decreased in size until it disappeared. Concurrent with reduction of the cyst, ascites developed. The patient displayed several traditional URSMS indicators including abnormal bladder and dysplastic kidneys. Our findings give additional insight into the embryology of urorectogenital development. Specifically, they suggest that the cystic mass may have been a persistent urachus prior to septation of the cloaca. Postnatal evaluation confirmed a URSMS diagnosis; the newborn had ambiguous genitalia, hypoplastic kidneys, absent uterus, imperforate anus, smooth perineum, and overall underdeveloped urogenital structures.

Comparisons between developmental studies rely on embryonic staging systems. It is important for comparison of molecular, immunohistochemical, and physiological studies of the developing chick intestine that the developmental stage of embryos is reliably determined. Good staging systems exist for the external features of the chick embryo but not for development of internal organs. To facilitate precise comparisons of chick embryo intestine development, we prepared an intestinal staging system. Embryos were fixed, other tissues dissected away, and the intestine and associated organs were then drawn to scale using a camera lucida. This produced black-and-white drawings with features of the gut clearly visible. The detailed drawings of intestine from chick embryos aged 2.5 to 10 days were correlated with age of embryos and developmental stages described in three common staging systems, Hamilton and Hamburger, Thompson and Fitzharris, and Allan and Newgreen. Descriptions of key changes in gut morphology and position are given for each stage. This staging of chick gut development will allow future studies to quote and compare development of the gut rather than external features or incubation time. This will allow much more precise reporting and comparisons in developmental studies of cell migration and gene expression.

In order to analyse the patterns of cellular proliferation both in the mesenchyme of the urorectal septum (URS) and in the adjacent territories (posterior urogenital mesenchyme, anterior intestinal mesenchyme and cloacal folds mesenchyme), as well as their contribution to the process of cloacal division, a computer-assisted method was used to obtain the nuclear area of 3874 mesenchymal cells from camera lucida drawings of nuclear contours of selected sections of human embryos [Carnegie stages (CSs) 13–18]. Based on changes in the size of the nucleus during the cellular cycle, we considered proliferating cells in each territory to be those with a nuclear area over the 75th percentile. The URS showed increasing cell proliferation, with proliferation patterns that coincided closely with cloacal folds mesenchyme, and with less overall proliferation than urogenital and intestinal mesenchymes. Furthermore, at CS 18, we observed the beginning of the rupture in the cloacal membrane; however, no fusion has been demonstrated either between the URS and the cloacal membrane or between the cloacal folds. The results suggest that cloacal division depends on a morphogenetic complex where the URS adjacent territories could determine septal displacement at the time that their mesenchymes could be partially incorporated within the proliferating URS.

To understand normal cloacal developmental processes, serial sagittal sections of mouse embryos were made every 6 hrs from embryonic day 11.5 (E11.5) to E13.5. During cloacal development to form the urogenital sinus and anorectal canal, fusion of the urorectal septum with the cloacal membrane was not observed, and the ventral and dorsal parts of the cloaca were continuously connected by the canal until disappearance of the cloacal membrane to open the vestibule formed by the urogenital sinus and anorectal canal to the outside at E13.5. Ventral shifting of the dorsal part of the cloaca was observed until E12.5. The dorsal part was transformed in accordance with ventral shifting. In addition, apoptosis was seen to occur around the dorsal part. However, from E12.25, apoptotic cells are observed in a linear arrangement in the urorectal septum just ventral to the peritoneal cavity. Interestingly, extension of this line reaches the area of the cloacal membrane disintegrated by apoptosis. The present findings suggest that in the early stages (until E12.0), distribution of apoptosis in mesenchyme around the dorsal part of the cloaca might be strongly related to the transformation and ventral shifting of this part. Conversely, the apoptosis pattern in urorectal septum mesenchyme in later stages (from E12.0) might be involved in transformation of the urorectal septum and disintegration of the cloacal membrane.

Omphalocele-exstrophy of the bladder (cloaca)-imperforate anus-spinal defects (OEIS) complex describes a rare grouping of more commonly occurring component malformations. We report two cases of OEIS complex diagnosed prenatally by ultrasound and magnetic resonance imaging (MRI). In both cases, OEIS complex was suspected by conventional sonography in the second trimester, and fetal MRI was performed at 27 and 32 weeks of gestation. Conventional sonography revealed low abdominal wall mass, spina bifida, absent bladder and ambiguous genitalia, but those findings were inconclusive. Using fetal MRI, we were able to detect omphalocele, imfraumbilical mass connected to gut tract, absent bladder, ambiguous external genitalia and spinal defect. Our findings suggest that fetal MRI is a useful tool for prenatal diagnosis of OEIS complex. MRI helps prenatal counseling and planning of postnatal early treatment strategy.

Background Previous studies of the tracheoesophageal sulcus and the sulci of the developing heart have suggested that the catenoidal or saddle-shaped configuration of the sulcus had mechanical properties that were important to developmental processes by causing regional growth limitation. We examined the development of the human perineal region to determine if a similar configuration exists in relation to the urorectal septum. We wished to re-examine the controversial issue of the role of the urorectal sulcus in the partitioning of the cloaca. Methods Digitally scanned photomicrographs of serial histologic sections of embryos from Carnegie stages 13, 15, 18, and 22, obtained from the Carnegie Embryological Collection were used. Each image was digitally stacked, aligned, and isolated using image-editing software. Images were compiled using 3-D image-visualization software (T-Vox), into full 3-D voxel-based volume renderings. Similarly, digital models were made of the urogenital sinus, anorectum, cloaca, allantois, mesonephric ducts, ureters, and kidneys by isolating their associated epithelium in each histologic section and compiling the data in T-Vox. Methods were developed to create registration models for determining the exact position and orientation of outlined structures within the embryos. Results Models were oriented and resectioned to determine the configuration of the urorectal sulcus. The results show that the urorectal sulcus maintains a catenoidal configuration during the developmental period studied and, thus, would be expected to limit caudal growth of the urorectal septum. Conclusion The observations support the concept that the urorectal septum is a passive structure that does not actively divide the cloaca into urogenital and anorectal components. Teratology 66:144–152, 2002. © 2002 Wiley-Liss, Inc.

Objectives To determine the anatomical steps leading to bladder agenesis in rats prenatally exposed as fetuses on gestational days (GD) 6–9 to adriamycin. Materials and methods Timed-pregnant Sprague–Dawley rats were injected intraperitoneally with adriamycin at 2 mg/kg (n = 28) on GD 6–9 (vaginal plug = day 0). The control group (n = 21) received saline. Fetuses were harvested on GD 10, 11, 12, 13, 14, 15 and 16. Serial paraffin sections were prepared from a minimum of 10 experimental and five control fetuses at each gestational age, and stained with either trichrome or haematoxylin and eosin, and examined by light microscopy. Results In the control group the urorectal septum first became visible and the mesonephric ducts apparently abutting the anterior cloaca on GD 12. The presumptive urinary bladder was clearly defined on GD 14. On GD 15, the common excretory ducts became incorporated into the newly formed urogenital sinus and the ureters opened into the bladder. In the treated animals, beginning on GD 11, the undivided cloaca was noticeably smaller and by GD 13–14, the vesical extension of the urogenital sinus was conspicuously absent. Instead, opposite ureters joined to drain directly into the proximal blind-ending urethra or the persistent distal urogenital sinus. Conclusions Prenatal exposure of rat fetuses to adriamycin resulted in primary agenesis rather than secondary resorption of the bladder. The ontogeny showed that the mechanism underpinning bladder development is unique and is under the influence of factors that can be targeted by adriamycin. Further work will elucidate the unique nature of bladder organogenesis and should have important applications in future research into artificial bladders.

OEIS complex refers to a combination of defects consisting of omphalocele, exstrophy of the cloaca, imperforate anus, and spinal defects. Possible embryologic mechanisms proposed for these findings have included: a single defect of early blastogenesis or a defect of mesodermal migration during the primitive streak period. Fourteen cases with OEIS complex and related malformations were reviewed for demographic features, prenatal and family histories, and clinical, radiological and pathological findings including the frequency and types of associated anomalies. The pathogenetic mechanisms causing OEIS complex and related malformations, such as anorectal and spinal defects, are discussed. The findings in these cases illustrate the spectrum of defects that can occur in the embryologic development of the cloaca and the urorectal septum. Differences in the timing and extent of mesenchymal ingrowth as well as cloacal membrane rupture may account for these variable findings. A developmental field defect involving the intraembryonic mesoderm suggests a possible etiologic role for homeobox genes, such as HLXB9 with mutations, resulting in anorectal and spine abnormalities, or retinoic acid receptors. OEIS complex with its mostly sporadic occurrence suggests etiologic heterogeneity with a possible role for environmental and genetic causes.

The motility of the avian cloaca is under neural control, but little is known about the neural network that accomplishes this function. This present study was designed to determine the distribution of nitric oxide-synthesising neurons in the pigeon cloaca by enzyme histochemistry for reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d). NADPH-d-positive staining was seen in the neurons and fibres in the cloaca. The highest density of nerve fibres was noted in the coprodeum and the lowest in the proctodeum. In the coprodeum, NADPH-d neurons were found singly, formed small groups of 2-10 neurons, or were seen in plexuses in the muscle layer, lamina propria, or around the arterioles. Several NADPH-d-positive neurons were also observed in the ganglia of the cloaca. NADPH-d fibres ran in the muscle layer, lamina muscularis mucosae and lamina propria, or surrounded blood vessels. The distribution pattern of acetylcholinesterase (AChE)-stained neurons and fibres in the cloaca was similar to that of NADPH-d. Double staining for NADPH-d and AChE showed colocalisation of the 2 enzymes in many neurons of the cloaca. Tyrosine hydroxylase (TH)-immunoreactive nerve fibres originating outside the cloaca were also noted. In the urodeum and proctodeum, neurons or fibres positive for NADPH-d, AChE or TH were scattered in the lamina propria. Nerve fibres immunoreactive for calcitonin-gene related peptide, galanin, methionine-enkephalin, substance P, and vasoactive intestinal peptide were found sparsely in the cloaca. Our results demonstrate that nitrergic neurons constitute a subpopulation which is closely associated with the cholinergic system in the pigeon cloaca.

Various endodermal sites posterior to the caudal-most somite were marked in ovo with the vital dye Dil, and the fate of marked endoderm was analyzed after 2 or 3 days' reincubation. The endoderm in this area became gut epithelium posterior to the caudal jejunum and yolk sac. The area occupied by the cells that were to contribute to the dorsal part of the digestive tube lay centrally around the area overlaid by axial and paraxial mesoderm, with the preventral digestive area lying outside with considerable overlapping, which was surrounded by the preyolk sac area. During the formation of the posterior digestive tube, the endoderm was elongated anteroposteriorly to a considerable degree. Cells that contributed to the cloaca and those that produced descendants in the large intestine occupied similar areas posterior to the center of the sinus rhomboidalis, which were included in the pre-ileal area extending more anteriorly. Prejejunal cells generally localized in a more anterior position than pre-ileal cells. Pre-allantoic cells were located in a rather small area around the posterior primitive streak.

Exstrophy of the cloaca is a dramatic malformation whose embryology is poorly understood. While the management of this disorder has received significant attention in the urology and general surgery literature, the neurologic status of these children has been poorly addressed. In order to better characterize the spinal cord and vertebral column malformations found in children with exstrophy of the cloaca, we undertook a clinical review of 26 consecutive children with exstrophy of the cloaca who had been seen at a single institution over 28 years. The prevalence of vertebral malformations in the 25 children who could be evaluated was 25/25 (100%). Twenty (80%) of the children had at least one vertebral fusion, most frequently at T-7. Twenty-two (88%) of the children had at least one vertebra with deficient posterior elements, and the spinal levels most frequently involved were S-2, S-3, S-4, and S-5. Nine (36%) of the children had at least one vertebra with a narrowed interpedicular distance, most frequently at T-7. Nine (36%) of the children had at least one vertebra with atrophic facet anatomy, most frequently at L-3. The prevalence of myelodysplasia in the 19 children for whom spinal magnetic resonance imaging or intraoperative findings were available was 100%. Of these 19 children, 15 (79%) had myelocystocele, 2 (11%) had a lipomeningocele, 2 (11%) had a meningocele, 2 (11%) had hydromyelia, and 4 (21%) had a tethered cord. These data suggest that spinal cord and vertebral column malformations are very common in children with exstrophy of the cloaca. Teratology 55:241-248, 1997. © 1997 Wiley-Liss, Inc.

We report the prenatal diagnosis, pathology, cytogenetics, and molecular studies of a retroperitoneal fetus in fetu. Prenatal ultrasonography of the host fetus in the third trimester showed an anencephalic, acardiac mass with identifiable extremities and spine within an intra-abdominal cystic mass. Pathological examination revealed a fetiform mass weighing 20 g with four extremities, digits, vertebral bodies, an oral cavity with developing teeth, primitive male external genitalia, a urinary bladder, a cloaca with an external opening, large intestines, a membranous capsule, and an umbilical cord with one artery, one vein, and Wharton's jelly. Histological examination demonstrated nerve bundles in the fibrocollagenous tissue below the cuboidal surface epithelium of the membranous capsule, and absence of lamina elastica interna and vasa vasorum in the single artery of the umbilical cord. Both the host infant and the fetus in fetu had a normal 46,XY karyotype. Molecular analysis using informative genetic markers showed no genetic difference between the host infant and the fetiform mass. We report this case as an unusual example of fetus in fetu in co-existence with an amnion-like membrane containing nerve bundles and with a well-formed umbilical cord. We demonstrate that fetus in fetu can be diagnosed prenatally if the fetiform mass has well-developed limbs and spine. We emphasize the necessity for suspicion of fetus in fetu when a well-defined encapsulated cystic mass with calcified solid components is detected prenatally in a fetus by ultrasonography.

The purpose of this work has been to establish the pattern of prenatal growth and normal development of the digestive tract and annex glands during goat embryonic stages. 21 embryos with ages ranging from 14 to 34 days (1.69 to 5.90 cm CR) as determined by registering the mating time, were obtained by cesarean section. This material was histologically processed to obtain complete serial sections of the stomatodaeum, foregut, midgut, hindgut and cloaca. In this work, it is chronologically described the morphogenesis and histogenesis of the mouth, hypophysis, pharynx and its derivatives, stomach, intestine, liver, pancreas and cloaca. The results obtained establish chronological comparisons with the development of the lamb and gives information on the unitary origin of the gastric compartments in ruminants.

Objective To report further applications of total urogenital sinus mobilization, earlier described as an easier method to correct a cloaca. Patients and methods Seven children (six girls and one boy, mean age 4 years, range 3 months to 10.5 years) underwent surgery and were followed for a mean of 1 year; their diagnoses included persistent cloaca and congenital adrenal hyperplasia (CAH) in two each, and a urogenital sinus (UGS), bladder exstrophy and penile agenesis in one each. The UGS is approached through a posterior sagittal incision and dissected circumferentially to the retropubic space, allowing the UGS to descend. It is then excised and separate openings of the vagina and urethra created. This technique is applicable to a UGS of ≤3 cm. Results In all patients, separate openings for the urethra and vagina were created. In three patients urinary continence was preserved after surgery. The patient with bladder exstrophy remains incontinent. The remaining patients are too young to assess (not yet toilet-trained). Conclusion This technique simplifies the surgical correction of UGS malformation; we confirm its usefulness in cases of persistent cloaca. It is also valuable in patients with CAH, primary UGS and in selected patients with bladder exstrophy and penile agenesis. When the UGS is not associated with a cloaca, the procedure can be performed perineally. Despite circumferential mobilization of the UGS, urinary continence is preserved.

Cloacal exstrophy, unilateral renal agenesis, and Müllerian anomalies occurred in a liveborn infant with a 47,XXX chromosome constitution. The patient extends the range of genitourinary anomalies reported in triple-X patients. Screening asymptomatic patients for urinary tract abnormalities may be useful in searching for silent malformations potentially associated with this karyotype.

Case report A healthy 24-year-old secundigravida presented for a routine ultrasound examination at the 11th week of gestation. The scan showed a singleton pregnancy and the crown-rump length (43.8 mm) was compatible with the gestation calculated from the last menstrual period. The foetal abdomen was distended by the presence of one only cyst (12 × 7.4 mm), compatible with distension of the bladder. There was no other evident abnormality. Amniotic fluid volume was normal for the first trimester despite total urethral obstruction. At 14 weeks still birth was found and the patient delivered three days later. Diagnosis was confirmed at autopsy. Post mortem examination confirmed a phenotypically normal male foetus consistent with 14 weeks gestation and weighing 70 gr. The abdomen was distended and the abdominal wall was thin. Internal examination confirmed the presence of an enlarged bladder. There was urethral atresia, with associated dilatation of the bladder but the ureter and kidneys were normal. Internal genitals were male with normal testicles and penis. Chromosome analysis was performed on foetal skin and karyotype was 46, XY. Discussion Cloacal dysgenesis sequence (CDS) is a rare cause of fetal obstructive uropathy (FOU). The prenatal differentition of CDS from other FOU is important because CDS is not amenable to in utero surgical intervention in the form of vescicoamniotic shounts. Differential diagnosis must be made with pathologies capable of determining cystic lesions localised in the inferior foetal abdomen, such as ovarian cysts, intestinal duplications, Hirschsprung disease, colic dilatation, imperforate hymen with hydrometracolps and megacystes–microcolon syndrome. Accurate prenatal diagnosis can be difficult and requires prolonged serial observations. The above-mentioned pathologies have characteristics of relative ‘fixity’, while typical imaging of cloaca undegoes variations due to sequential filling in, or repletion, of the liquid contained in the urinary, genital and digestive components of the malformation. Moreover, intestinal obstruction is generally associated with polyhydramnios. In the first trimester diagnosis of cloaca anomalies are very difficult because there are no great changes in amniotic fluid volume and ascites rarely is present; serial examinations are required for enable definition of diagnosis.

We report the prenatal diagnosis of a fetus with persistent cloaca, prune belly sequence, and anencephaly. This fetus resembles the recently reported patient with prune belly and anencephaly. A syndromic diagnosis was not possible in either case, but the likelihood of a chance association also has to be regarded as low.

OEIS complex (exstrophy of the cloaca) is an association of fetal malformations that includes omphalocele, exstrophy of the bladder, imperforate anus, and spinal defects. Most cases should be prenatally detectable by maternal serum alpha-fetoprotein screening, but an accurate diagnosis is essential for appropriate counselling of the family.

Summary .1. An abnormality of the hind end of the body in a female is described. 2. The various theories relating' to the development of this region and their relative values in explaining the malformations found, are discussed. 3 The suggestion is put forward that fusion of the Mullerian ducts is responsible for the separation of the hind gut from the ventral cloaca, and that further development of the hind end is associated with changes occurring in the distal ends of those ducts. The grounds on which such a suggestion is based are, firstly the conditions found in this specimen, and, secondly, its value in solving certain of the problems connected with the malformations recorded.

The anatomy of the lymphatic system of the snake is described, together with some preliminary observations of the blood vascular system. Lymphatic vessels are numerous and thin-walled, chiefly periangious, but some are in close relation to the vertebral, column. The aortic lymphatic enlarges to form a sac in the abdominal region which encloses several of the viscera and in many cases communicates with their connective tissue sheaths. Lymph vessels in the skin and body musculature form a regularly arranged segmental network. The system communicates with the blood vascular system in two places: by means of a pair of posterior lymph hearts in the region of the cloaca, and at the jugular lymph sac just craniad to the heart. The arrangement and distribution of lymphatic structures is of interest in relation to phylogenetic development and because of the specialization of structure due to the elongate form of the snake.

A morphological and histochemical investigation was conducted on the pronephros and mesonephros of the mouse embryo from 8.5 through 16.5 days. The pronephros appeared between days 8.5 and 9.5 as a thickening of the somatic layer of the intermediate cell mass. It consisted of three small clusters of cells on either side of the midline dorsally between the somite and the coelom, at the level of somites 8 and 9. The mesonephros arose during day 9 and persisted until day 16. In the male the anterior three tubules were incorporated into the testis at 15.5–16.5 days. The mesonephros consisted of approximately 11 tubules located between somites 10–17. The tubules possessed lumina and connected with the Wolffian duct. Indications of internal and external glomeruli were noted on day 11. The Wolffian duct reached the cloaca at ten days. Strong alkaline phosphatase activity was noted in the differentiating tubules. Cytoplasmic and luminal enzyme activity was observed between 9.3 and 12.5 days indicating possible function at this time. Acid phosphatase was demonstrable in the tubules and duct only on day 11. Ribonucleic acid was observed in the nuclei and cytoplasm of the mesodermal cells as they differentiated into tubules and duct. A decrease in RNA was noted after differentiation was complete. Periodic acid-Schiff material (diastase-stable) was localized in the basement membrane of the tubule and duct cells. A faint positive reaction was also found at the luminal border of the tubules. The strongest reaction was noted in the luminal border at 11.5–12.5 days. Those tubules being incorporated into the genital system in the male were also PAS positive. Morphological and histochemical evidence suggested that the mouse mesonephros, though quasi vestigial, may function for a short time.

SYNOPSIS This report describes three variants of an anomaly variously known as vesico-intestinal fissure and extrophy of the cloaca. The embryology is not well understood, and the mortality is high because of the complexities of management and the frequent occurrence of other major malformations.

The unusual delivery of a dead second twin with rare malformations is presented. the first twin, born live following a normal labor, had no malformations. the birth of the second twin was obstructed by massive ascites, and its abdomen had to be perforated before delivery. the sex could not be determined due to lack of the internal genitalia and the fetal appearance of the external genitals. the left kidney and ureter were hypoplastic. the right ureter and distal part of the colon were dilated and opened into a large primitive cystic cloaca without communication to the exterior. the ascites was probably caused by the urinary obstruction. These malformations probably represent one of the earliest arrested developments of the embryonic hind-gut. the presence of a tracheo-esophageal fistula and a single umbilical artery, together with the anal atresia and the renal anomalies, could indicate that the anomalies formed part of the VATER association.