Establishment of the Digestive System Flashcards
The first indication in the formation of the digestive tract is initiated by the establishment of the ____
endodermal layer of the blastocyst
The mesoderm splits into somatic and splanchnic layers where the splanchnic layer become closely associated with the endoderm as the _____
splanchnopleure
The intraembryonic tube, lined by endoderm and covered by splanchnic mesoderm
Primitive Gut
Gives rise to the epithelial lining of the digestive tract
ENDODERM
Forms connective tissue and smooth muscle components of the digestive tract wall
SPLANCHNIC MESODERM
- The cranial portion lying beneath the head
- The first part of the primitive gut to be definitely incorporated into the embryo
foregut
*foregut
Ends blindly, but has communication with the undifferentiated part of the gut called ____
anterior intestinal portal
*foregut
Closed cranially by the ____ which is lined by endoderm on the inside and covered by ectoderm on the outside.
oro-pharyngeal membrane
*foregut
An ectodermal depression at the location of the oro- pharyngeal membrane, the ____, later develops into the oral cavity.
stomodaeum
- A connecting portion between the foregut and the hindgut
- Opens into the yolk sac
- The last to acquire its floor through the lateral body folds
Midgut
- Formed in similar manner as the foregut beneath the caudal portion of the embryo.
- The posterior intestinal portal is its communication with the rest of the gut.
Hindgut
*hindgut
Also blind, being closed by the _____, similarly lined by endoderm and covered by ectoderm.
cloacal membrane
*hindgut
A depression at the site of the cloacal membrane, the _____, develops into the anus and the opening of the uro-genital system.
proctodaeum
- Extends from the developing pharynx, where it opens dorsal to the larynx, to the spindle-shaped primordium of the stomach.
- Its principal morphogenic development is elongation.
Esophagus
*Species differentiation
Coated by skeletal muscle throughout its
length (____),
to the diaphragm (____),
to the mid-thorax (____),
or not at all (____).
dog, ruminants
pig
cat, horse, human
avian
Develops as a spindle-shaped dilation of the more caudal portion of the foregut, becoming evident during the third week of gestation in the pig.
Stomach
- The ____ develops as an expansion of the fundus, and a caudoventral pocket of the developing rumen forms the ____.
- The _____ develops as a bulge along the lesser curvature.
The rest of the stomach becomes _____.
rumen
reticulum
omasum
abomasum
The liver and the pancreas both develop from ____ and ____ that originate from the most caudal region of the foregut.
dorsal and a ventral endodermal buds