Early embryonic development 2

Question 1

Define bilaminar disk

Answer 1

The Epiblast and hypoblast. Derived from the embryoblast. This will later become the trilaminar disk with the formation of the primitive streak.

Question 2

Define germ layer

Answer 2

A layer from which other developed tissues originated from

Question 3

Define ectoderm

Answer 3

Outermost germ layer of cells

Question 4

What does the ectoderm become?

Answer 4

Epidermis
Nerve tissue
Retina of eye

Question 5

Define endoderm

Answer 5

Innermost germ layer of cells

Question 6

What does the endoderm become?

Answer 6

GI lining

Glands associated with gut

Question 7

Define dorsal surface

Answer 7

The outermost surface during early development

Question 8

Define ventral surface

Answer 8

The innermost surface during early development

Question 9

Define mesoderm

Answer 9

Middle germ layer of cells

Question 10

What does the mesoderm become?

Answer 10

Muscle
Bone
Cartilage
Blood vessels
Urogenital tract

Question 11

Define primitive streak

Answer 11

A narrow groove that develops on the dorsal surface of the Epiblast. It has an important role in the orientation of the embryo, determining the front and the back.

Question 12

Define gastrulation

Answer 12

The reorganisation of the germ layers into the ectoderm, mesoderm and endoderm and hence establishing the origin of all tissues

Question 13

Define trilaminar disk

Answer 13

The three germ layers. Ectoderm, mesoderm and endoderm.

Question 14

What is the first step in gastrulation?

Answer 14

Appearance of the primitive streak

Question 15

Which surface does the primitive streak form on?

Answer 15

Dorsal

Question 16

Which end of the primitive streak is the primitive node at?

Answer 16

Cranial end

Question 17

Which end of the primitive streak is the primitive pit at?

Answer 17

Caudal end

Question 18

When does the primitive streak regress?

Answer 18

As gastrulation proceeds and the 3 germ layers are produced

Question 19

Which direction does development go in?

Answer 19

Cranial to caudal

Question 20

How is the trilaminar disc formed?

Answer 20

Cells on the epiblast migrate to the primitive streak

Invaginate into the epiblast and displace the hypoblast to create the mesoderm

Question 21

Why are there 2 gaps in the mesoderm layer?

Answer 21

One is for the future mouth and the other is for the future anus

Question 22

What is the notochord?

Answer 22

Basis for the axial skeleton
Drives formation of the nervous system
Defines the midline
Important signalling role

Question 23

The notochord regresses, where is it in the adult?

Answer 23

Nucleus pulposus of the intervertebral discs

Question 24

What is the primitive node responsible for?

Answer 24

Molecular signals which control patterning and orientation (axes)