The development of the cloaca in the human embryo

Rack1-mediated ferroptosis affects hindgut development in rats with anorectal malformations: Spatial transcriptome insights

Anorectal malformation (ARM), a common congenital anomaly of the digestive tract, is a result of insufficient elongation of the urorectal septum. The cytoplasmic protein Receptor of Activated C-Kinase 1 (Rack1) is involved in embryonic neural development; however, its role in embryonic digestive tract development and ARM formation is unexplored. Our study explored the hindgut development and cell death mechanisms in ARM-affected rats using spatial transcriptome analysis. We induced ARM in rats by administering ethylenethiourea via gavage on gestational day (GD) 10. On GDs 14-16, embryos from both normal and ARM groups underwent spatial transcriptome sequencing, which identified key genes and signalling pathways. Rack1 exhibited significant interactions among differentially expressed genes on GDs 15 and 16. Reduced Rack1 expression in the ARM-affected hindgut, verified by Rack1 silencing in intestinal epithelial cells, led to increased P38 phosphorylation and activation of the MAPK signalling pathway. The suppression of this pathway downregulated Nqo1 and Gpx4 expression, resulting in elevated intracellular levels of ferrous ions, reactive oxygen species (ROS) and lipid peroxides. Downregulation of Gpx4 expression in the ARM hindgut, coupled with Rack1 co-localisation and consistent mitochondrial morphology, indicated ferroptosis. In summary, Rack1, acting as a hub gene, modulates ferrous ions, lipid peroxides, and ROS via the P38-MAPK/Nqo1/Gpx4 axis. This modulation induces ferroptosis in intestinal epithelial cells, potentially influencing hindgut development during ARM onset.

Cloacal Dysgenesis Sequence in a Preterm Neonate

BACKGROUND Cloaca malformations result from a disproportion of apoptosis, cell growth, and maturation. The range of cloacal malformations is extensive and diverse, with a lack of a straightforward classification system. Cloacal dysgenesis sequence (CDS), also known as urorectal septum malformation sequence, is a rare cloaca variant described as the absence of a perineal orifice. Prenatal magnetic resonance imaging and antenatal ultrasounds may reveal a cloacal malformation; however, many patients are not diagnosed with cloacal malformation until birth. CASE REPORT We present a case of a female neonate delivered by a 23-year-old G2P1T1A0L0 mother who had received comprehensive prenatal care. During pregnancy, bilateral multicystic dysplastic kidneys were identified prenatally, leading to the in utero placement of a vesicoamniotic shunt. The physical exam revealed a distended abdomen with reduced abdominal musculature and laxity, ascites, a vesicoamniotic shunt in place, absent urethra, ambiguous genitalia with no vaginal opening, no perineal opening, and clubfoot. Abdominal radiograph showed findings consistent with significant abdominal ascites. An exploratory laparotomy was performed that included diverting colostomy, mucous fistula creation, tube vaginostomy, removal of the vesicoamniotic shunt, and suprapubic tube placement. The patient recovered well from this operation with no complications. CONCLUSIONS CDS is an uncommon condition in pediatric patients, and although sonographic findings can reveal urinary tract abnormalities, prenatal imaging might not always identify CDS. Our case underscores the uniqueness of the case and the significance of early detection and immediate medical and surgical intervention.

Antenatal diagnosis of hydrometrocolpos with Mullerian duplication on ultrasound and fetal MRI: case report and literature review

Fetal abdomino-pelvic cystic lesions are uncommon and can have varied etio-pathogenesis. Most commonly they originate from the gastrointestinal or genitourinary tract. These include choledochal cyst, hydronephrosis, renal cyst, mesenteric/omental cyst, ovarian cyst, meconium pseudocyst, and hydrocolpos/hydrometrocolpos among others. Fetal hydrometrocolpos is rare with a reported incidence of 0.006% and its diagnosis requires a high index of suspicion. Antenatal ultrasound and magnetic resonance imaging (MRI) is invaluable in diagnostic evaluation. This case report describes the imaging features of antenatally detected congenital hydrometrocolpos with Mullerian duplication secondary to cloacal malformation using antenatal ultrasound and MRI. Per-operative findings and other possible differential diagnoses are discussed along with a brief review of literature.

Feto-placental Unit: From Development to Function

The placenta is an intriguing organ that allows us to survive intrauterine life. This essential organ connects both mother and fetus and plays a crucial role in maternal and fetal well-being. This chapter presents an overview of the morphological and functional aspects of human placental development. First, we describe early human placental development and the characterization of the cell types found in the human placenta. Second, the human placenta from the second trimester to the term of gestation is reviewed, focusing on the morphology and specific pathologies that affect the placenta. Finally, we focus on the placenta's primary functions, such as oxygen and nutrient transport, and their importance for placental development.

Investigation of the risk factors of anorectal malformations

PURPOSE

To investigate the factors that influence the occurrence of anorectal malformations (ARMs).

METHODS

From December 2018 to December 2019, 136 children treated for ARMs at the Children's Hospital of Chongqing Medical University were included in the case group. The control group consisted of children with intussusception or perianal abscesses. A uniform questionnaire was filled by the parents of the enrolled children.

RESULTS

The birth weight of the cases was significantly lower than that of the controls (p < .01), and children with ARMs were more likely to be complicated with single umbilical artery (SUA) (p < .001). Maternal upper respiratory tract infection (adjusted odds ratio [OR_adj ], 2.44; 95% confidence interval [CI], 1.29-4.63) and urogenital infection (OR_adj , 2.67; 95% CI 1.11-6.38) during the first trimester of pregnancy, anemia during pregnancy (OR_adj , 5.69; 95% CI, 1.01-32.07), and exposure to hazardous substances 6 months before pregnancy and during the first trimester of pregnancy (OR_adj , 13.82; 95% CI, 3.86-49.35) are associated with increased risk of ARMs. Folic acid supplements (OR_adj , 0.31; 95% CI, 0.14-0.65) and multivitamin (OR_adj , 0.34; 95% CI, 0.15-0.79) had a protective effect on ARMs. Paternal drug use (OR_adj , 9.17; 95% CI, 2.19-38.49) 6 months before their wives' conception increased the risk of ARMs.

CONCLUSION

Maternal infection, anemia during pregnancy, and maternal hazardous substances exposure are possible risk factors for ARMs. Folic acid supplements and multivitamin can reduce the occurrence of ARMs. Meanwhile, paternal drug use may also be a risk factor for ARMs.

Kidney development to kidney organoids and back again

Kidney organoid technology has led to a renaissance in kidney developmental biology. The complex underpinnings of mammalian kidney development have provided a framework for the generation of kidney cells and tissues from human pluripotent stem cells. Termed kidney organoids, these 3-dimensional structures contain kidney-specific cell types distributed similarly to in vivo architecture. The adult human kidney forms from the reciprocal induction of two disparate tissues, the metanephric mesenchyme (MM) and ureteric bud (UB), to form nephrons and collecting ducts, respectively. Although nephrons and collecting ducts are derived from the intermediate mesoderm (IM), their development deviates in time and space to impart distinctive inductive signaling for which separate differentiation protocols are required. Here we summarize the directed differentiation protocols which generate nephron kidney organoids and collecting duct kidney organoids, making note of similarities as much as differences. We discuss limitations of these present approaches and discuss future directions to improve kidney organoid technology, including a greater understanding of anterior IM and its derivatives to enable an improved differentiation protocol to collecting duct organoids for which historic and future developmental biology studies will be instrumental.

Genome-Wide Survey for Microdeletions or -Duplications in 155 Patients with Lower Urinary Tract Obstructions (LUTO)

Lower urinary tract obstruction (LUTO) is, in most cases, caused by anatomical blockage of the bladder outlet. The most common form are posterior urethral valves (PUVs), a male-limited phenotype. Here, we surveyed the genome of 155 LUTO patients to identify disease-causing CNVs. Raw intensity data were collected for CNVs detected in LUTO patients and 4.392 healthy controls using CNVPartition, QuantiSNP and PennCNV. Overlapping CNVs between patients and controls were discarded. Additional filtering implicated CNV frequency in the database of genomic variants, gene content and final visual inspection detecting 37 ultra-rare CNVs. After, prioritization qPCR analysis confirmed 3 microduplications, all detected in PUV patients. One microduplication (5q23.2) occurred de novo in the two remaining microduplications found on chromosome 1p36.21 and 10q23.31. Parental DNA was not available for segregation analysis. All three duplications comprised 11 coding genes: four human specific lncRNA and one microRNA. Three coding genes (FBLIM1, SLC16A12, SNCAIP) and the microRNA MIR107 have previously been shown to be expressed in the developing urinary tract of mouse embryos. We propose that duplications, rare or de novo, contribute to PUV formation, a male-limited phenotype.

A case report: Common channel anomaly with vaginal agenesis and rectal stone after posterior sagittal anorectoplasty (PSARP)

Introduction and importance

We reported a case of common channel anomaly complicated with vaginal agenesis and rectal stone, which is a long-term complication of PSARP, a combination of very rare conditions with high morbidity and especially difficult treatment.

Presentation of case

A 15-year-old female presented with a chief complaint of cyclic abdominal pain. The patient had no history of menstruation before. Physical examination showed a common channel. The diameter of the common channel was approximately 1 cm and 0.3 cm in length. A sound (±2 mm thickness) was inserted to the small opening between the urethra and anal mucosa with the length of the canal 6 cm. At the end of the opening, a stone-like structure was felt. The management of this case was abdominal hysterectomy with right salpingectomy and stone evacuation.

Discussion

Cloacal malformation is thought to be associated with vaginal agenesis since both malformations are considered to have a similar pathophysiologic background. Treatment can be performed using posterior sagittal combined with laparotomy approach. After surgery, patients will need a long-term follow-up since the conditions may be associated with many possible urologic and gynecologic comorbidities, including recurrent urinary tract infections, hematosalpinx, and vesicourethral reflux, including stone formation.

Conclusion

Our case was considered one of the most complex common channel anomalies because it was complicated with a rare condition called vaginal agenesis and rectal stone after PSARP. A multidiscipline approach was necessary.

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Common channel anomaly with vaginal agenesis and rectal stone after PSARP is a complex rare condition.

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Requiring multiple diagnostic modalities

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Multidiscipline approach was needed.

Case Report: Mucinous Adenocarcinoma Arising From Congenital Ejaculatory Duct Cyst

Herein we present a previously unreported rare case of mucinous adenocarcinoma arising from a congenital ejaculatory duct cyst. Radiographic and endoscopic examinations revealed the tumor occurred in a cyst running through the prostate. Initially, the immunohistochemical pathology results showed that it was a metastatic mucinous adenocarcinoma, but no other primary lesions were clinically evidenced. Based on the embryonic development process of the male urogenital tract, the malformation of the patient's ejaculatory duct, and the pathological examination of the resected specimen, we considered the tumor to be a primary mucinous adenocarcinoma which originating from the hypoplastic ejaculatory duct. The tumor may have developed from the foci of intestinal metaplasia from cloacal remnants during embryonic development.

The embryology of persistent cloaca and urogenital sinus malformations

Cloacal malformations are characterized by the confluence of the lower urinary tract, the female reproductive tract, and the rectum to create a common channel with a single opening on the perineum. The presence of a cloaca is a normal phase of early human embryological development. Between the 4^th and 7^th weeks of gestation, the cloaca undergoes subdivision to form the hindgut and urogenital sinus. Failure of this process results in the congenital anomaly termed persistent cloaca (PC). The term urorectal septum malformation sequence (URSMS) is also used to describe this anomaly. The classic description of this process which is still cited in many standard textbooks dates from the 19^th century. However, this has been increasingly called into question by the findings of studies using modern scientific methodology. Urogenital sinus anomalies are defined by the confluence of the urethra and vagina to form a common channel of varying length with a single perineal opening. In this condition, the anorectal canal opens separately on the perineum. The presence of a urogenital sinus represents a transient phase of the normal development of the lower genital tract in the female fetus. However, the form of urogenital sinus most commonly encountered in the developed world is a feature of disordered sexual differentiation and does not arise simply from the persistence of the anatomical structure which is a feature of normal fetal development.

Extrinsic innervation of the pelvic organs in the lesser pelvis of human embryos

Realistic models to understand the developmental appearance of the pelvic nervous system in mammals are scarce. We visualized the development of the inferior hypogastric plexus and its preganglionic connections in human embryos at 4-8 weeks post-fertilization, using Amira 3D reconstruction and Cinema 4D-remodelling software. We defined the embryonic lesser pelvis as the pelvic area caudal to both umbilical arteries and containing the hindgut. Neural crest cells (NCCs) appeared dorsolateral to the median sacral artery near vertebra S1 at ~5 weeks and had extended to vertebra S5 1 day later. Once para-arterial, NCCs either formed sympathetic ganglia or continued to migrate ventrally to the pre-arterial region, where they formed large bilateral inferior hypogastric ganglionic cell clusters (IHGCs). Unlike more cranial pre-aortic plexuses, both IHGCs did not merge because the 'pelvic pouch', a temporary caudal extension of the peritoneal cavity, interposed. Although NCCs in the sacral area started to migrate later, they reached their pre-arterial position simultaneously with the NCCs in the thoracolumbar regions. Accordingly, the superior hypogastric nerve, a caudal extension of the lumbar splanchnic nerves along the superior rectal artery, contacted the IHGCs only 1 day later than the lumbar splanchnic nerves contacted the inferior mesenteric ganglion. The superior hypogastric nerve subsequently splits to become the superior hypogastric plexus. The IHGCs had two additional sources of preganglionic innervation, of which the pelvic splanchnic nerves arrived at ~6.5 weeks and the sacral splanchnic nerves only at ~8 weeks. After all preganglionic connections had formed, separate parts of the inferior hypogastric plexus formed at the bladder neck and distal hindgut.

Development of extrinsic innervation in the abdominal intestines of human embryos

Compared to the intrinsic enteric nervous system (ENS), development of the extrinsic ENS is poorly documented, even though its presence is easily detectable with histological techniques. We visualised its development in human embryos and foetuses of 4–9.5 weeks post‐fertilisation using Amira 3D‐reconstruction and Cinema 4D‐remodelling software. The extrinsic ENS originated from small, basophilic neural crest cells (NCCs) that migrated to the para‐aortic region and then continued ventrally to the pre‐aortic region, where they formed autonomic pre‐aortic plexuses. From here, nerve fibres extended along the ventral abdominal arteries and finally connected to the intrinsic system. Schwann cell precursors (SCPs), a subgroup of NCCs that migrate on nerve fibres, showed region‐specific differences in differentiation. SCPs developed into scattered chromaffin cells of the adrenal medulla dorsolateral to the coeliac artery (CA) and into more tightly packed chromaffin cells of the para‐aortic bodies ventrolateral to the inferior mesenteric artery (IMA), with reciprocal topographic gradients between both fates. The extrinsic ENS first extended along the CA and then along the superior mesenteric artery (SMA) and IMA 5 days later. Apart from the branch to the caecum, extrinsic nerves did not extend along SMA branches in the herniated parts of the midgut until the gut loops had returned in the abdominal cavity, suggesting a permissive role of the intraperitoneal environment. Accordingly, extrinsic innervation had not yet reached the distal (colonic) loop of the midgut at 9.5 weeks development. Based on intrinsic ENS‐dependent architectural remodelling of the gut layers, extrinsic innervation followed intrinsic innervation 3–4 Carnegie stages later.

Cloacal Malformation in Female Children: Outcome of Initial Management

Objective:

To document our experience of initial management of Cloacal malformation in female patients.

Methods:

A descriptive retrospective study was conducted in the Department of Pediatric Surgery of the National Institute of Child Health Karachi from January 2010 to September 2018. Female patients with diagnosis of Cloacal malformation were included in this study. Data regarding the age at presentation, mode of presentation, clinical features, presence of hydrocolpos, and associated anomalies were noted. Surgical procedures performed in these patients and the outcomes were also documented. Data was analyzed on SPSS Version 20.

Results:

Sixty females were included in the study. Age ranged from birth to three years with a median of four days. Patients admitted through emergency were 44 (73.33%) while 16 (26.66%) were admitted through outpatient clinic. Hydrocolpos was found in 15 (25.00%) patients. Five (8.33%) patients had massive abdominal distention and were presented with severe respiratory distress. Among them three had massive hydrocolpos, one patient had pneumoperitoneum secondary to Meckel’s perforation and one patient was having massive colonic dilatation. Hydronephrosis and hydroureter were found in 14 (23.33%) patients, while dilated bladder was found in three (5.00%) patients. After optimization of patients, bowel diversion was done as transverse colostomy in 39 (65.00%) patients, high sigmoid colostomy in 17(28.33%) patients while ileostomy was done in three (5.00%) patients. All patients with hydrocolpos had tube vaginostomy. None of the patients required bladder diversion and urinary tract dilatations were gradually subsided in nine patients in the post-operative period. Associated anomalies were found in 22(36.66%) of cases predominantly of sacral origin. Operative complications were found in 18(30.00%) patients, including stoma site in infection in 12(20.00%) patients, vaginal tube dislodgement in two patients, wrong placement of tube in one patient and vaginostomy stenosis in one case. While bowel stoma retraction occurred in four patients, prolapsed was found in three patients. Renal failure occurred in one patient. In total, 37(61.00%) patients had smooth recovery, 18(30.00%) patients had some complications, while Five (8.33%) patients were expired due to sepsis.

Conclusions:

Majority of cloacal malformations present in neonatal life. Initial management is an important step in dealing with these patients. Care must be taken during the abdominal exploration regarding drainage of hydrocolpos and appropriate placement of bowel stoma.

Duplex kidney formation: developmental mechanisms and genetic predisposition

Congenital abnormalities of the kidney and urinary tract (CAKUT) are a highly diverse group of diseases that together belong to the most common abnormalities detected in the new-born child. Consistent with this diversity, CAKUT are caused by mutations in a large number of genes and present a wide spectrum of phenotypes. In this review, we will focus on duplex kidneys, a relatively frequent form of CAKUT that is often asymptomatic but predisposes to vesicoureteral reflux and hydronephrosis. We will summarise the molecular programs responsible for ureter induction, review the genes that have been identified as risk factors in duplex kidney formation and discuss molecular and cellular mechanisms that may lead to this malformation.

The development of the dorsal mesentery in human embryos and fetuses

The vertebrate intestine has a continuous dorsal mesentery between pharynx and anus that facilitates intestinal mobility. Based on width and fate the dorsal mesentery can be subdivided into that of the caudal foregut, midgut, and hindgut. The dorsal mesentery of stomach and duodenum is wide and topographically complex due to strong and asymmetric growth of the stomach. The associated formation of the lesser sac partitions the dorsal mesentery into the right-sided "caval fold" that serves as conduit for the inferior caval vein and the left-sided mesogastrium. The thin dorsal mesentery of the midgut originates between the base of the superior and inferior mesenteric arteries, and follows the transient increase in intestinal growth that results in small-intestinal looping, intestinal herniation and, subsequently, return. The following fixation of a large portion of the abdominal dorsal mesentery to the dorsal peritoneal wall by adhesion and fusion is only seen in primates and is often incomplete. Adhesion and fusion of mesothelial surfaces in the lesser pelvis results in the formation of the "mesorectum". Whether Toldt's and Denonvilliers' "fasciae of fusion" identify the location of the original mesothelial surfaces or, alternatively, represent the effects of postnatal wear and tear due to intestinal motility and intra-abdominal pressure changes, remains to be shown. "Malrotations" are characterized by growth defects of the intestinal loops with an ischemic origin and a narrow mesenteric root due to insufficient adhesion and fusion.