Normal and Abnormal Development of the Biliary Tree
Gianfranco Alpini, Domenico Alvaro, Marco Marzioni, Gene LeSage, Nicholas LaRusso in The Pathophysiology of Biliary Epithelia, 2020
The chronology for development of the biliary tree is given in (Table 2) On the 18th day of gestation in the human embryo, when the embryo is 2.5 mm in length, the ventral floor of the distal foregut thickens and begins to protrude, forming the hepatic diverticulum. Over the next few days, this endodermal sprout grows in a cranioventral fashion towards the septum transversum, a mesenchymal plate that incompletely separates the thoracic cavity from the abdominal cavity.15 The endodermal cells invade the mesoderm of the septum transversum as ramifying cords of cells, coincidental with the ingrowth of a sinusoidal vascular network from tributaries of the vitelline vein. The nascent liver is thus formed, and over the next three weeks of gestation grows rapidly and soon fills most of the abdominal cavity. The liver corpus separates from the septum transversum in the process; the mesenchymal residua becomes the diaphragm.
Congenital thoracic deformities
Prem Puri in Newborn Surgery, 2017
In thoracoabdominal ectopia cordis, also known as pentalogy of Cantrell, the heart is covered by skin or an omphalocele-like membrane. It is associated with a constellation of anomalies. The classic pentalogy includes the following: (1) a midline, supraumbilical abdominal wall defect; (2) a defect of the lower sternum; (3) a deficiency of the anterior diaphragm (absence of septum transversum); (4) a defect in the diaphragmatic pericardium; and (5) congenital intracardiac defects. All five anomalies may not be present, and there can be an incomplete expression of the syndrome.4 In contrast with thoracic ectopia cordis, the heart is covered and lacks severe anterior displacement and cephalic orientation. The world literature on ectopia cordis has been extensively reviewed previously.5
The Diaphragm Muscle
Alan D. Miller, Armand L. Bianchi, Beverly P. Bishop in Neural Control of the Respiratory Muscles, 2019
The diaphragm muscle (DIAm) is a complex structure separating the thoracic and abdominal cavities, hence the Greek meaning “to span a partition”. The DIAm appears rather late in evolution, being present only in mammals, while other vertebrates use different means of ventilation. The DIAm is embryologically derived from the mesoderm, with the muscular and tendonous portions having a composite origin. The central tendon arises from the septum transversum which also contributes to the derivation of the pericardium and connective tissue of the liver, thus the close association between the DIAm and these thoracic and abdominal structures. The muscular portion of the DIAm derives from myotomes of the cervical spinal cord, and then makes its long descent to ultimately gain a broad range of attachment at the thoracic and lumbar levels. The innervation of the DIAm arises from its cervical site of origin and follows the long descent of the muscle. The mechanical actions of the DIAm are as complex as its multiple sites of origin and insertion. Its major function is in inspiration, although the DIAm is also involved in several nonventilatory motor behaviors including coughing, defecation, emesis, micturition, parturition, sneezing, vocalization, and weight lifting.
Embryogenesis of Ectopic Bronchogenic Cysts: Keep It Simple
Published in Journal of Investigative Surgery, 2020
Cohn et al. [2] provide the classical theory that bronchogenic cysts are generated as a result of abnormal bronchial budding of the small lung bud given from the ventral wall of the pharynx. Others have proposed an origin from an accessory lung bud [3] or from an accessory bronchus [4]. Besides, it should be understood that the primitive trachea and esophagus are packed in a mass of mesenchyme, which will be the future mediastinum. The mediastinum tissue is continuous with the root of the neck cephalad, and the septum transversum just below; the latter will form the tendinous center of the diaphragm. It follows that a detached bronchogenic cyst can be found in these regions, such as at the bifurcation of the trachea (most common), the posterior mediastinum, the chest wall [4]. The cyst may also abandon the diaphragm to invade the abdominal cavity, and end intraperitoneally or extraperitoneally, thus found in the liver or the adrenal gland [4].
Fabrication of a co-culture micro-bioreactor device for efficient hepatic differentiation of human induced pluripotent stem cells (hiPSCs)
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Mousa Kehtari, Bahman Zeynali, Masoud Soleimani, Mahboubeh Kabiri, Ehsan Seyedjafari
During embryonic development, endothelial cells envelope liver bud-derived hepatoblasts and stimulate bud’s expansion and invasion into surrounding septum transversum mesenchyme [15]. Several studies have demonstrated that co-culturing primary hepatocytes or stem cells-derived hepatocyte-like cells with endothelial cells maintain hepatocyte maturation via paracrine signalling and cell–cell contacts [6,16]. On the other hand, in hepatic tissue, hepatocytes are permanently exposed to portal pressure in the form of fluid shear stress [17]. Despite the evidence indicating the importance of fluid shear stress on phenotype maintenance and metabolic activity of hepatocytes [18–20], few studies evaluated this factor in the hepatic differentiation.
Related Knowledge Centers
- Mesenchyme
- Phrenic Nerve
- Pleuroperitoneal
- Skull
- Embryo
- Mesentery
- Myogenesis
- Thoracic Diaphragm
- Ventral Ramus of Spinal Nerve
- Central Tendon of Diaphragm