Lecture 6

Question 1

Describe the developement of the airways:

Answer 1

1. A tracheobronchal groove will bud of the primative foregut
2. Once fully broken it is a tracheo-bronchal tube
3. Then branches approximately thirty more times to become the structure that is the lung

Question 2

Describe the developemental stages of the midgut:

Answer 2

1. Midgut develops and herniates extra-embryonically for a short period of time
2. Gut twists 90 degree so that caudal limb overlays the cranial limb for a period of time
3. The caeum develops in the caudal limb
4. The gut then turns another 180 degrees

Question 3

Describe the order of the portions of the small intestine:

Answer 3

Dueodenum then jejenum and then the ileum

Question 4

Describe the rotation of the stomach:

Answer 4

1. Rotates 90 degrees counter clockwise when viewed from dorsal aspect around a cranial- caudal aspect
2. The stomach then rotates around a 90 degree counter clockwise aspect when viewed dorsally around dorso-ventral axis

Question 5

What does the dorsal mesogastrium eventually become?

Answer 5

Becomes the greater omentum

Question 6

What does the ventral mesogastrium eventually become?

Answer 6

Eventually becomes the lesser omentum

Question 7

Describe the embryological developement of the anus:

Answer 7

1. Terminal hindgut dilates to form cloaca connected to the allantois
2. Cloaca is dividied by the ingrowth of a uro-rectal septum into a urogenital sinus (cranially) and an anorectal canal caudally

Question 8

Describe the embryological development of the kidney:

Answer 8

1. The intermediate mesoderm forms the mesonephric ridge
2. 3 succesive pairs of kidneys will form. The most cranial being the pronephros, only the last one persists as a definitive adult kidney (pronephros, mesonephros and metanephros)
3. The uteric bud, buds of the mesonephric duct, then dilates to form the renal pelvis and the collecting ducts
4. The mesonephric duct persists to form the male ductus deferens

Question 9

How does the descendtion of the male testes occur?

Answer 9

The testes descend through a vaginal process, through the inguinal canal, drawn by a long mesenchymal cord known as the gubernaculum

Question 10

How are the female genitalia normally formed?

Answer 10

The vagina buds of the urogenital sinus normally formed by the fusion of the paramesonephric duct.

Question 11

The male and female genitalia both form in a very simmilar way. What is distinct about the formation of the male genitalia?

Answer 11

Male genitalia form by the fusion of the urogenital fold