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Paediatric Urology
Published in Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed, MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
Jemma Hale, Arash K. Taghizadeh
The abnormalities seen in bladder exstrophy represent a failure of development of the lower abdominal wall; possibly because of the failure of mesoderm to migrate into the cloacal membrane. In classic bladder exstrophy the abnormalities seen all follow from this failure. The bladder lies open and exposed as a bladder plate. The umbilicus lies immediately adjacent to the bladder plate. When the bladder plate is mobilised for closure the umbilicus becomes ischaemic and is subsequently lost. The ureters do not enter the bladder obliquely and there is an increased tendency to subsequent vesicoureteric reflux. There is diastasis of the pubic rami, (i.e., they fail to meet in the midline). The lower abdominal wall demonstrates a series of characteristic features: the rectus muscle divaricates inferiorly, the umbilicus is sited rather low, and the perineum is foreshortened resulting in a slightly anterior anus. The separated pubic rami result in the bony attachments of the corpora cavernosa being widely separated. This contributes to a rather short and wide penis in boys, and a bifid clitoris in girls.
Urology
Published in Stephan Strobel, Lewis Spitz, Stephen D. Marks, Great Ormond Street Handbook of Paediatrics, 2019
Maldevelopment of the cloacal membrane and lower abdominal wall results in a spectrum ranging from epispadias (1 in 120,000), through vesical exstrophy (1 in 50,000) to cloacal exstrophy (1 in 300,000 live births).
3.0: The development of gastric systems in children
Published in Clarissa Martin, Terence Dovey, Angela Southall, Clarissa Martin, Paediatric Gastrointestinal Disorders, 2019
Shomik Ghosal, Adrian G Martin
Beginning in the fifth week the mesoderm develops into the urorectal septum. The formation of the urorectal septum results in the division of the cloaca; the cloaca divides into a ventral primitive urogenital sinus and a dorsal primitive anorectal canal. In the seventh week the cloacal membrane breaks down. In the site of the former cloacal membrane, ectoderm becomes the epithelium of the anal canal.
Difference between right-sided and left-sided colorectal cancers: from embryology to molecular subtype
Published in Expert Review of Anticancer Therapy, 2018
Seung Yoon Yang, Min Soo Cho, Nam Kyu Kim
The endodermal gut tube created by body folding during the fourth week of gestation consists of a blind-ended cranial foregut, a blind-ended caudal hindgut, and a midgut open to the yolk sac through the vitelline duct [11]. The midgut forms the distal duodenum, jejunum, ileum, cecum, ascending colon, and proximal two-thirds of the transverse colon. The hindgut forms the distal third of the transverse colon, the descending and sigmoid colon, and the upper two-thirds of the anorectal canal. Just superior to the cloacal membrane, the primitive gut tube forms an expansion called the cloaca. During the fourth to sixth weeks, a coronal urorectal septum partitions the cloaca into the urogenital sinus, which will give rise to urogenital structures, and a dorsal anorectal canal [12]. As the right and left sides of the colon derive from different embryologic origins, anatomically, the proximal colon receives its main blood supply from the superior mesenteric artery with its capillary network being multilayered. The distal colon is perfused by the inferior mesentery artery. Between these two main sources, there is a watershed area located just proximal to the splenic flexure where branches of the left branch of the middle colic artery anastomose with those of the left colic artery. This area represents the border of the embryologic midgut and hindgut. Venous drainage of the colon largely follows the arterial supply with superior and inferior mesenteric veins draining both the right and left halves of the colon.