L 24 - Development of the mouth and GIT in Embryo Flashcards
What are coeloms?
The early membrane-bound cavities of the early embryo
What are the three coeloms in an early embryo?
- pericardial coelom
- contains developing heart - Left and Right pleural canals
- contains the developing lungs - peritoneal coelom
- contains the developing abdominal viscera
What is the allantois?
The primitive hindgut
What needs to develop in order for the abdominal cavity to form?
Septum transversum
What are derivatives of the fore-gut?
Parts of the oral cavity Pharynx/Oesophagus Stomach/prox duodenum Liver and pancreas Thyroid/ parathyroid/thymus Trachea and Lungs
What are dervied from the mid-gut?
Duodenum to transverse colon (cranial mesentery artery)
What are derivatives from the hind-gut?
Distal part of transverse colon to descending colon
cloaca
- anal canal/urogential sinus
Caudal mesenteric artery
What is the stomodaeum?
Midline depression on the ventral surface of the head that is created by the cranial and lateral body folding
What is the epithelium that lines the mouth?
Ectodermal
What does the 1st Branchial arch make up?
= mandibular arch
Left/Right Maxillary process
Left/right Mandibular process
= elongation of these processes forms oral cavity
Which two processes fuse to make up the Upper jaw?
-Naso-medial process + Maxillary process
What fuses to make the nose?
Frontal process + naso-lateral process
What fuses to make up the lower jaw?
Mandibular process fuse from left and right
What fuse to make the naso-lacrimal duct?
Naso-lateral process + maxillary process
What determines the grooves in different upper lips of animals?
Naso-medial processes
What are the 3 mesenchymal swellings that make up the tongue?
- Median tongue swelling = ectoderm
- Two lateral tongue swellings = ectoderm
- hypopharyngeal swellings = endoderm
What do the Median tongue swelling and lateral tongue swellings make up?
The body of the tongue
is Median tongue swelling important in Herbivores?
Yes, it makes up the torus.
Not as important for carnivours
Where do the connective tissues of the esophagus come from?
Derived partially from splanchnic mesoderm
Where is the striated muscle of the oesophagus derived?
Caudal branchial arches
Where is the epithelium and glands of the oesophagus derived?
Endoderm
Where does the stomach begin during formation - and how does it end up?
Begins midline - then shifts caudally. Then rotates so that the greater curvature is ventral and lies on the left hand side
What is a mesogastrium?
mesentery of the embryonic stomach
Dorsal = greater omasum
Ventral = lesser omasum
What is the pancreas derived from?
2 primordia originates from two different sides 1) Really close to liver 2) Other from duodenum Eventually they merge
What happens during intestine formation once the small intestines is pushed back into abdominal cavity?
Whole thing ends up twisting 270 degrees so that they go all the way around the mesenteric artery
What is a proctodeum?
invagination of ectoderm beneath tail
What is the cloacal membrane made out of?
endoderm/ectoderm
What is Atresia ani?
membranes to not dissolve and get closed in bum hole
