L 24 - Development of the mouth and GIT in Embryo

Question 1

What are coeloms?

Answer 1

The early membrane-bound cavities of the early embryo

Question 2

What are the three coeloms in an early embryo?

Answer 2

1. pericardial coelom
   - contains developing heart
2. Left and Right pleural canals
   - contains the developing lungs
3. peritoneal coelom
   - contains the developing abdominal viscera

Question 3

What is the allantois?

Answer 3

The primitive hindgut

Question 4

What needs to develop in order for the abdominal cavity to form?

Answer 4

Septum transversum

Question 5

What are derivatives of the fore-gut?

Answer 5

Parts of the oral cavity
Pharynx/Oesophagus
Stomach/prox duodenum
Liver and pancreas 
Thyroid/ parathyroid/thymus
Trachea and Lungs

Question 6

What are dervied from the mid-gut?

Answer 6

Duodenum to transverse colon (cranial mesentery artery)

Question 7

What are derivatives from the hind-gut?

Answer 7

Distal part of transverse colon to descending colon
cloaca
- anal canal/urogential sinus
Caudal mesenteric artery

Question 8

What is the stomodaeum?

Answer 8

Midline depression on the ventral surface of the head that is created by the cranial and lateral body folding

Question 9

What is the epithelium that lines the mouth?

Answer 9

Ectodermal

Question 10

What does the 1st Branchial arch make up?

Answer 10

= mandibular arch
Left/Right Maxillary process
Left/right Mandibular process
= elongation of these processes forms oral cavity

Question 11

Which two processes fuse to make up the Upper jaw?

Answer 11

-Naso-medial process + Maxillary process

Question 12

What fuses to make the nose?

Answer 12

Frontal process + naso-lateral process

Question 13

What fuses to make up the lower jaw?

Answer 13

Mandibular process fuse from left and right

Question 14

What fuse to make the naso-lacrimal duct?

Answer 14

Naso-lateral process + maxillary process

Question 15

What determines the grooves in different upper lips of animals?

Answer 15

Naso-medial processes

Question 16

What are the 3 mesenchymal swellings that make up the tongue?

Answer 16

1. Median tongue swelling = ectoderm
2. Two lateral tongue swellings = ectoderm
3. hypopharyngeal swellings = endoderm

Question 17

What do the Median tongue swelling and lateral tongue swellings make up?

Answer 17

The body of the tongue

Question 18

is Median tongue swelling important in Herbivores?

Answer 18

Yes, it makes up the torus.

Not as important for carnivours

Question 19

Where do the connective tissues of the esophagus come from?

Answer 19

Derived partially from splanchnic mesoderm

Question 20

Where is the striated muscle of the oesophagus derived?

Answer 20

Caudal branchial arches

Question 21

Where is the epithelium and glands of the oesophagus derived?

Answer 21

Endoderm

Question 22

Where does the stomach begin during formation - and how does it end up?

Answer 22

Begins midline - then shifts caudally. Then rotates so that the greater curvature is ventral and lies on the left hand side

Question 23

What is a mesogastrium?

Answer 23

mesentery of the embryonic stomach
Dorsal = greater omasum
Ventral = lesser omasum

Question 24

What is the pancreas derived from?

Answer 24

2 primordia 
 originates from two different sides 
	1) Really close to liver
	2) Other from duodenum 
Eventually they merge

Question 25

What happens during intestine formation once the small intestines is pushed back into abdominal cavity?

Answer 25

Whole thing ends up twisting 270 degrees so that they go all the way around the mesenteric artery

Question 26

What is a proctodeum?

Answer 26

invagination of ectoderm beneath tail

Question 27

What is the cloacal membrane made out of?

Answer 27

endoderm/ectoderm

Question 28

What is Atresia ani?

Answer 28

membranes to not dissolve and get closed in bum hole