Late Embryogenesis

Question 1

Transformation of the bilaminar germ disc to trilaminar germ disc is by the process of ………

Answer 1

gastrulation

Question 2

The primitive streak is clearly visible in an embry of …… age

Answer 2

15 to 16 day embryo

Question 3

Some cells displace the hypoblast to form the ………

Answer 3

endoderm

Question 4

Cells come to lie between the ………….. and ………. to become the mesoderm

Answer 4

epiblast and the newly formed endoderm

Question 5

The ectoderm is formed by ………..

Answer 5

cells remaining in the epiblast

Question 6

Oropharyngeal membrane consists of ……….

Answer 6

tightly adherent ectoderm and endoderm

Question 7

Where does the prechordial plate form?

Answer 7

The prechordial plate forms between the tip of the notochord and the oropharyngeal membrane.

Question 8

……….. induces the formation of the forebrain

Answer 8

The prechordial plate

Question 9

The notochord underlines the ……….

Answer 9

Neural tube

Question 10

…………. induces the formation of the neural tube and the axial skeleton

Answer 10

Notochord

Question 11

Where is the cloacal membrane is formed?

Answer 11

at the caudal end of the embryonic disc

Question 12

The cloacal membrane is similar in structure to the ………..

Answer 12

oropharyngeal membrane

Question 13

…………. temporarily connects the amniotic cavity and the yolk sac cavities at the primitive pit

Answer 13

The Neurenteric canal

Question 14

Describe the allantois

Answer 14

• it is a small diverticulum of the posterior wall of the yolk sac that extends into the connecting stalk
• It is rudimentary
• It appears around the 16th day of development following appearance of the Cloacal membrane
• it may be involved in the abnormalities of the urinary bladder

Question 15

The allantois appears around the ……… day of development

Answer 15

16th day

Question 16

The extraembryonic mesoderm lining the cytotrophoblast and amion is called …………

Answer 16

extraembryonic somatopleuric mesoderm

Question 17

The extraembryonic mesoderm lining the primary yolk sac is called ………….

Answer 17

extraembryonic splanchnopleuric mesoderm

Question 18

How is the secondary or definitive yolk sac formed?

Answer 18

The hypoblast proliferate and form a new cavity within the primary yolk sac and the new cavity is called secondary or definitive yolk sac

Question 19

……… expands and forms a large cavity called chorionic cavity

Answer 19

Extraembryonic coelom

Question 20

With development of blood vessels, connecting stalk becomes ……………

Answer 20

the umbilical cord