Embryologic development of the mesentery, peritoneal reflection, and Toldt's fascia
John Calvin Coffey, Rishabh Sehgal, Dara Walsh in Mesenteric Principles of Gastrointestinal Surgery, 2017
A further process must occur once the gastromesenteric complex has assumed its position within the abdominal cavity, that is, attachment. At present, this is understood to comprise two major events, the development of the peritoneal reflection and Toldt's fascia. When the mesentery returns to its final adult position a gap is present between the surface of the mesentery and the abdominal wall. In the adult, this gap is bridged by an extensive peritoneal reflection, a layer of mesothelium that extends from the mesenteric surface (or intestinal surface) to the abdominal wall. The peritoneal reflection occurs at the base of the small intestinal region of mesentery, where it attaches to the posterior abdominal wall. It continues around the ileocecal junction and back up around the right colon as the right peritoneal reflection. From there, it continues around the upper surface of the hepatic flexure. It then continues across the upper surface of the transverse colon, between this and the greater omentum. At the splenic flexure, it continues as the splenocolic reflection, which in turn continues along the lateral aspect of the left colon as the left peritoneal reflection. From here, the reflection continues into the pelvis as the left pararectal pelvic reflection. A peritoneal reflection also occurs on the right side of the mesosigmoid and continues into the pelvis as the right pararectal reflection. The right and left peritoneal reflection coalesce as the anterior reflection in the pouch of Douglas.
The vermiform appendix
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie in Bailey & Love's Short Practice of Surgery, 2018
The mesentery of the appendix or mesoappendix arises from the lower surface of the mesentery or the terminal ileum and is itself subject to great variation. Sometimes, as much as the distal one-third of the appendix is bereft of mesoappen- dix. Especially in childhood, the mesoappendix is so transparent that the contained blood vessels can be seen (Figure72.3). In many adults, it becomes laden with fat, which obscures these vessels. The appendicular artery, a branch of the lower division of the ileocolic artery, passes behind the terminal ileum to enter the mesoappendix a short distance from the base of the appendix. It then comes to lie in the free border of the mesoappendix. An accessory appendicular artery may be present but, in most people, the appendicular artery is an ‘end-artery', thrombosis of which results in necrosis of the appendix (synonym: gangrenous appendicitis). Four, six or more lymphatic channels traverse the mesoappendix to empty into the ileocaecal lymph nodes.
Complications of laparoscopic colorectal surgery
Mark Coleman, Tom Cecil, Brian Dunkin in Laparoscopic Colorectal Surgery, 2017
Most right-sided ileocolic anastomoses are performed extracorporeally, either stapled or hand sewn. This requires adequate mobilisation of both the terminal ileum and transverse colon with division of the right colic or right colic branch of the middle colic. Failure to adequately mobilise the colon can lead to damage of the mesentery and its blood supply and technical difficulty in performing the anastomosis if the bowel cannot be adequately delivered out of the abdomen. Care needs to be taken to ensure there is no twist on the mesentery, and it is worth spending time prior to the specimen extraction to orientate and align the mobilised colon at the end of laparoscopic mobilisation. Right-sided colonic mobilisation with a medial to lateral approach can be challenging and tiring to surgeons on their learning curves, and it is important to concentrate for the anastomosis. Teamwork on the learning curve and recognition of surgeon fatigue are important in reducing anastomotic complications.
Transmesenteric hernia: a rare case of acute abdominal pain in children: a case report and review of the literature
Published in Acta Chirurgica Belgica, 2018
Edward Willems, Bart Willaert, Sam Van Slycke
Several possible explanations of the pathogenesis of mesenteric defects have been proposed, yet the exact etiology remains uncertain up to now. The most popular theory states that relative intestinal ischemia during fetal development leads to thinning of the peritoneal layers causing the formation of a defect in the mesentery [4,5,12]. A second possible explanation suggested by Federschmidt is the partial regression of the dorsal mesentery during fetal development of the human being. Other possible theories include the rapid lengthening of a mesenterial segment, intra-uterine compression of the mesentery by the colon during midgut herniation or coalescence between two epithelial layers with insufficient connective tissue between them [13,14]. Genetic predisposition has also been suggested, since associations with other genetic diseases such as cystic fibrosis and Hirschprung’s disease and with intestinal atresia have been reported [7].
Successful treatment of sclerosing mesenteritis with tamoxifen monotherapy
Published in Baylor University Medical Center Proceedings, 2023
Lauren Zammerilla Westcott, Dallas Wolford, Taylor G. Maloney, Ronald C. Jones
Sclerosing mesenteritis is a rare idiopathic disorder of fat necrosis, inflammation, and fibrosis of the mesentery. The etiology of the condition remains largely speculative; however, case reports attribute etiology most commonly to prior abdominal trauma or surgery, followed by malignancy and autoimmune conditions.1 While the disease is often asymptomatic, a subset of patients develop complications from the mass effect on gastrointestinal, mesenteric, vascular, or lymphatic structures.2 A small percentage of patients may develop further complications such as small bowel obstruction, chylous ascites, or superior mesenteric vein thrombosis.2 The differential diagnosis is broad and includes any cause of mesenteric edema, hemorrhage, or infiltration with inflammatory or neoplastic cells.3
Clinical importance of main pancreatic duct variants and possible correlation with pancreatic diseases
Published in Scandinavian Journal of Gastroenterology, 2020
Ana Dugic, Sara Nikolic, Steffen Mühldorfer, Milutin Bulajic, Raffaella Pozzi Mucelli, Apostolos V. Tsolakis, J.-Matthias Löhr, Miroslav Vujasinovic
Differentiation of pancreas begins at about 4–10 mm embryonic size, with outgrowth of dorsal and ventral bud from the primitive foregut, each having its own axial duct. Whereas the ventral anlage derives from hepatic diverticulum, the larger and more rostrally-located dorsal anlage lies in the dorsal mesentery. It is proposed that the ventral anlage consists of two buds (right and left), of which the left ventral bud usually regresses completely. Due to unequal growth of the duodenum, the right ventral bud rotates clockwise and backwards along with the common bile duct to reach its position in the dorsal mesentery, inferior and posterior to the dorsal bud. As a result, at about the 7th week of gestation, the dorsal and ventral buds fuse to form the pancreas. The dorsal bud gives rise to the tail, body, isthmus and the upper portion of the pancreatic head, whereas the ventral bud forms the lower part of the head. The origin of processus uncinatus is still disputable. While some authors state its dorsal origin, others propose its junctional origin (dorsoventral junction) [4–7].
Related Knowledge Centers
- Abdominal Wall
- Gastrointestinal Tract
- Histology
- Lymphatic Vessel
- Microscopy
- Peritoneum
- Electron Microscope
- Blood Vessel
- Adipose Tissue
- Nerve