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Embryology, Anatomy, and Physiology of the Bladder
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Allan Johnston, Tarik Amer, Omar Aboumarzouk, Hashim Hashim
There are two theories to explain the separation process:Rathke and Tourneux (the traditional theory)An upper fold (Tourneux) develops caudally.Two lateral (Rathke) folds fuse at the cloacal wall midline forming the urorectal septum.Completed when the urorectal septum fuses with the cloacal membrane by 5−6 weeks’ gestation.Kluth and van der PutteBoth suggested that there is neither a descending septum nor a lateral walls fusion. These studies aimed at determining the cause of congenital anorectal malformations.
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.
The digestive system and the respiratory system
Published in Frank J. Dye, Human Life Before Birth, 2019
A large part of the colon and the rectum have their origins in the hindgut (Figure 16.6). The caudal end of the hindgut is a blind tube ending at the cloacal membrane, the boundary between the rectum and the proctodeum (an inpocketing of ectoderm on the ventral side of the tail end of the embryo). The portion of the hindgut near the cloacal membrane is called the cloaca. From the cloaca's ventral surface, the allantoic diverticulum extends for a short distance into the umbilical cord. The urorectal septum grows between the hindgut and allantoic diverticulum toward the cloacal membrane, separating the cloacal membrane into an anal membrane and a urogenital membrane (see Figure 16.6). When the anal membrane ruptures during the seventh week, the anus opens to provide a passageway from the digestive tube into the amniotic fluid.
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.
Fetal hydrops – a review and a clinical approach to identifying the cause
Published in Expert Opinion on Orphan Drugs, 2020
Esther Dempsey, Tessa Homfray, John M Simpson, Steve Jeffery, Sahar Mansour, Pia Ostergaard
Urorectal septum malformation sequence (URSMS) leading to meconium peritonitis and nonimmune fetal hydrops was first reported in 2006 [166]. Subsequently multiple papers looking at the etiology of all fetal hydrops cases attribute a small percentage (2-3%) to ‘urogenital malformations’, including prune-belly syndrome, renal agenesis, neonatal Bartter syndrome and cystic kidney disease [2,72,167–169]. Still, nonimmune fetal hydrops is an unusual presentation of urogenital tract malformations. There is little published in the literature which explores the relationship between urogenital malformations and fetal hydrops, or which attempts to explain the pathophysiology of the edema.
The Allantois and Urachus: Histological Study Using Human Embryo and Fetuses
Published in Fetal and Pediatric Pathology, 2022
Xuelai Liu, Xianghui Xie, Zhe-Wu Jin, Huan Wang, Yanbiao Song, Peng Zhao, Long Li
At GA 8 weeks, the abdominal wall remained opened through the umbilical cord, and the embryo was bent ventrally due to the development of the sacrococcygeal region (Fig. 2A and B). The allantois became an enclosed pouch located within the intraembryonic cavity (Fig. 2C, asterisk). The allantois and the developing rectum were lined with a continuous layer of epithelium, but these two structures were partitioned by the urorectal septum, which grew toward the cloaca (Fig. 2D, arrow).