Development Of ody Cavities, Respiratory, And Digestive Systems Flashcards
Intraembryonic coelom
. Forms as space btwsplanchnic and somatic layers of lat. plate mesoderm
. Subdivided into pericardial, pleural, and abdominopelvic cavities
When is transverse folding of embryo complete?
end of Week 4
Lateral body wall folds vs. lateral splanchnic folds
. Body wall folds from somatic mesoderm plus overlying ectoderm, fuses closing ventral body wall, parietal serous membrane from somatic mesoderm
. Splanchnic folds from splanchnic mesoderm plus underlying endoderm fuses forming gut tube, visceral serous membrane from splanchnic mesoderm
Dorsal mesentery
. Where parietal and visceral serous membranes are continous w/ one another
. Suspends gut tube from post. Body wall
. Derived from splanchnic mesoderm
Ventral mesentery
. Present along foregut
. Persists in area of future stomach and liver
. Derives from septum transversum
Septum transversum
. Thick plate mesoderm proliferates in space btw thoracic cavity and yolk sac
. Partially separates thoracic and abdominopelvic cavities
Pericardioperitoneal canals
. Bilateral openings in septum transversum on either side of foregut
. Lung buds from gut tube project into these canals
Pleuropericardial folds
. Bilateral mesodermal folds projecting from lat. wall of thoracic cavity ant. To lung buds and post. To developing heart
. Expand med. to come pleuropericardial membranes
Pleuropericardial membranes
. Engulf phrenic n. And common cardinal v.
. Fuse at midline w/ roots of lungs
. Fusions divides thoracic cavity into pericardial cavity and 2 pleural cavities
. Incorporate into fibrous pericardium
Formation of thoracoabdominal diaphragm
. Pleuroperitoneal folds (mesodermal) project into caudal ends of pericardioperitoneal canals and extend med. and ventrally
. Pleuroperitoneal membranes form post. Part of Diaphragm in week 7
. Membranes, septum transversum, and mesentery of esophagus fuse o separate pleural and peritoneal cavities
. Myoblasts (C305 somites) migrate along lat. wall and into membranes to form muscular part
. Fibers of C3-5 spinal nn. Migrate in myoblasts to form phrenic n.
. Septum transversum becomes central tendon
Congenital diaphragmatic hernia
. Most common diaphragm hernia
. Failure of pleuroperitoneal membranes to close off pericardioperitoneal canals
. Abdominal contents protrude into abdominal cavity and compress heart and lungs
. High mortality from units not forming well
Parasternal hernias
. Small defects in muscle fibers of diaphragm permit intestinal loops to enter chest btw sternal and costal parts of diaphragm
Esophageal hernias
. Congenitally short esophagus causes upper stomach to remain in thorax
Endoderm in gut tube
. Forms epithelial lining of GIa nd respiratory tracts
Splanchnic mesoderm in gut tube gives rise to ___
. . Smooth muscle, CT of GI and respiratory tracts
. Organs that arise as outpouching of these tracts
. Dorsal mesentery of gut tube
When does Vitelline duct incorporate into umbilical cord and degenerate w/ yolk sac?
Months 2-3