12.9 Anatomy: Embryology 2

Question 1

What does the endoerm form?

Answer 1

Epithelial lining, organ forms along with mesodermal tissue

Question 2

What comprises the coelom?

What happens at one month?

Answer 2

Yolk sac, bilaminar disc, amniotic cavity

C-shaped tube

Question 3

What gives rise to the body wall?

Answer 3

Somatic mesoderm

Ectoderm

Question 4

What gives rise to the viscera?

Answer 4

Splanchnic mesoderm

Endoderm

Question 5

How is the coelom formed?

Answer 5

Yolk sac separates from embryo (purse string)

Space that gets pinched off is gut lumen

Question 6

When are mouth and anus formed?

Answer 6

After 3 weeks of age (ectoderm meets endoderm)

Question 7

What divides rectum from urogenital tract?

Answer 7

Urorectal septum

Question 8

Where does the allantois lie? What does it do? What does it give rise to?

Answer 8

Lies in the body stalk, stores nitrogenous waste in some species (not humans)

Gives rise to bladder an d urogenital tract

Question 9

What do pharangyeal arches become?

Answer 9

Gill remnants (jaws, face)

Question 10

What is the pharynx lined with?

What forms from it?

Answer 10

Endoderm

Four pouches

Question 11

What are derivatives of the pharyngeal arches?

Answer 11

Ear canal, tonsils and thymus

Question 12

How does the heart initially form?

Answer 12

Two endocardial tubes are brought together in the midline (fusion produces heart)

Question 13

How common are congenital heart defects? What is the most dcommon?

Answer 13

1:200

25% are ventricular septal defects (L/R division)

Question 14

How does the GIT form?

Answer 14

Rotation around axis of yolk stalk and SMA (large folds across small intestine)

Question 15

What is omphalocele?

Answer 15

Failure of gut to retract back, GIT outside of body

1:25000

Question 16

How do the trachea, lungs, liver and pancreas initially appear as?

Answer 16

Endodermal out-pocketings

Question 17

What causes situs invertus? How common is it?

Answer 17

Cilia generating currents from R to L (primitive groove sets symmetry)

Question 18

What first appears in development of kidneys and ureters?

Answer 18

Pronephros

Question 19

What does the mesonephros consist of?

Answer 19

Kidney and ureters (connects to developing testes in males)

Question 20

What does the penis for by?

Answer 20

Fusion of urogenital folds

Question 21

What is hypospadiasis? How common is it?

Answer 21

Only partial fusion of urogential folds, urethral opening on base of penis

1:300

Question 22

When do the ectoderm, mesoderm and endoderm form?

Answer 22

Week 2-3

Question 23

When is major organogenesis complete by?

Answer 23

By 3 months (1st trimester)