Ebook Textbook of clinical embryology: Part 2
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Ebook Textbook of clinical embryology: Part 2
13JOverviewI he digestive tract (gastrointestinal tract) develops from pnml tlve gut that Is derived from the dorsal part of endodermal yolk sac.I he Ebook Textbook of clinical embryology: Part 2 primitive gut fomis during the fourth week of mtrauter me life by the Incorporation of a larger portion of the yolk sac (umbilical vesicle) Into the embryonic disc during cranlocaudal and lateral folding of embryo (Fig. 13.1). The tubular primitive gut extends in the median plane from buccopharynge Ebook Textbook of clinical embryology: Part 2al membrane at its cranial end to cloacal membrane at its caudal end.It freely communicates with the remaining yolk sac by the vitellointestinal duct.Ebook Textbook of clinical embryology: Part 2
The part ol gut cranial to this communication is called foregut, part caudal to this communication is called hindgut. and part intervening between lor13JOverviewI he digestive tract (gastrointestinal tract) develops from pnml tlve gut that Is derived from the dorsal part of endodermal yolk sac.I he Ebook Textbook of clinical embryology: Part 2d of hindgut is separated from the proctodeum by cloaca! membrane.At later stage ol development buccopluiryugeal and cloaca! membranes rupture, and gut communicates to exterior at its both ends.The endoderm of primitive gut forms the endothelial lining of all Jxirts of rhe gastrointestinal tract exc Ebook Textbook of clinical embryology: Part 2ept |>arr of month and distal Jxirr of anal canal that arc derived from ectoderm of stemodeum and proctodeum. rcs|>ccrivcly.The muscular, connective tEbook Textbook of clinical embryology: Part 2
issues, and other layers of wall of rhe digestive tract are derived from splanch-noplcuric mesoderm surrounding rhe primitive gut (Fig. 13.2).While rh13JOverviewI he digestive tract (gastrointestinal tract) develops from pnml tlve gut that Is derived from the dorsal part of endodermal yolk sac.I he Ebook Textbook of clinical embryology: Part 2 right up to the yolk sac and are, therefore, termed vitelline arteries. Later most ol these ventral branches ol dorsal aorta disappear and only three of them remain: one of foregul (the celiac artery), one of midgut (the superior mesenteric artery), and one of hindgut (the inferior mesenteric arter Ebook Textbook of clinical embryology: Part 2y) (Fig. 13.3).The development of digestive (gastrointestinal) tract showing foregur, midgut, and hindgur along with pri-mordia of structures derivedEbook Textbook of clinical embryology: Part 2
from them is shown in Fig. 13-4.N.B. Molecular regulation of regional differentiation of primitive gut to form its different parts Is done by Hox and 13JOverviewI he digestive tract (gastrointestinal tract) develops from pnml tlve gut that Is derived from the dorsal part of endodermal yolk sac.I he Ebook Textbook of clinical embryology: Part 2c disc during its folding. Note that amniotic cavity covers the embryonic disc on all side except at the umbilical opening. B. Subdivisions of primitive gut into foregut, midgut, and hindgut. Note midgut communicates with the remaining yolk sac via vitellointestinal duct.The derivatives of the foreg Ebook Textbook of clinical embryology: Part 2ut, midgut, and hindgut are given in Table 13.1 and shown in Figs 13.4 and 13.5.N.B. Ibe junction between the foregut and midgut IS known as anteriorEbook Textbook of clinical embryology: Part 2
intestinal portal, whose position in adult gut corresponds with the termination of the bile duct in second part of the duodenum.The junction between t13JOverviewI he digestive tract (gastrointestinal tract) develops from pnml tlve gut that Is derived from the dorsal part of endodermal yolk sac.I he Ebook Textbook of clinical embryology: Part 2tal one-third of transverse colon, figure 13.5 shows vartous derivatives of abdominal part of the gut wrtth location of anterior and posterior intestinal portals.Development of Foregut DerivativesEsophagusThe esophagus develops from the part of foregut between the pharynx and rhe stomach. Vcntrally Ebook Textbook of clinical embryology: Part 2ar thePrimitive pharynxRespiratory diverticulumEsophagusI hyroid diverticulumStomachHepatic hudVentral and dorsalpancreatic budsMidgut loop (primary iEbook Textbook of clinical embryology: Part 2
ntestinal loop)Fig. 13.4 Schematic diagram of 5-mm embryo showing the formation of the digestive tract. Note the subdivisions of digestive tract into 13JOverviewI he digestive tract (gastrointestinal tract) develops from pnml tlve gut that Is derived from the dorsal part of endodermal yolk sac.I he Ebook Textbook of clinical embryology: Part 2hageal junction, the foregut presents a median laryngotracheal groove. The groove bulges forward and caudally to form tracheobronchial (respiratory) diverticulum. The tracheoesophageal septum divides the foregur caudal to the pharynx into theTable 13.1Derivatives of the three parts of the primitive Ebook Textbook of clinical embryology: Part 2gutPart of gutDerivativesForegut• Floor of mouth13JOverviewI he digestive tract (gastrointestinal tract) develops from pnml tlve gut that Is derived from the dorsal part of endodermal yolk sac.I he 13JOverviewI he digestive tract (gastrointestinal tract) develops from pnml tlve gut that Is derived from the dorsal part of endodermal yolk sac.I heGọi ngay
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