embryology week three

Question 1

4 events in week 3

Answer 1

gastrulation & primitive streak formation, notochord formation, initial neural tube formation, initial mesodermal differentiation (body tissues)

Question 2

trilaminar embryonic disk

Answer 2

becomes a 3 layer disk, conversion of bilaminar disk

Question 3

gastrulation

Answer 3

formation of ectoderm, mesoderm, endoderm germ layers

Question 4

primitive streak

Answer 4

a raised groove on the dorsal surface of the epiblast, gastrulation begins with appearance

Question 5

endoderm

Answer 5

the first cells to migrate through the primitive streak and displace the underlying hypoblast cells

Question 6

mesoderm

Answer 6

layer between epiblast and endoderm by epiblast cells

Question 7

mesenchyme cells

Answer 7

star shaped cells that do not attach to one another, freely migrate within embryo

Question 8

ectoderm

Answer 8

cells remaining on dorsal surface of embryo

Question 9

endoderm & ectoderm structure

Answer 9

epithelial tissues, sheets of tightly joined cells

Question 10

mesoderm structure

Answer 10

mesenchyme tissue that consists of free cells capable of migrating within the embryo

Question 11

primitive node

Answer 11

a swelling located at the cranial end of the primitive streak

Question 12

notochord

Answer 12

cellular rod forms from mesodermal and endodermal cells

Question 13

nucleus pulposus

Answer 13

notochord after birth of the intervertebral discs

Question 14

neurulation

Answer 14

the developing notochord signals the overlying ectoderm to form the brain and spinal cord

Question 15

neural plate

Answer 15

ectoderm over the developing notochord thickens

Question 16

neural groove

Answer 16

inward folding of the neural plate

Question 17

(hollow) neural tube

Answer 17

deepening of the neural groove, pinched off at the dorsal surface of body

Question 18

neural crest

Answer 18

external to the closed neural tube, flattened mass formed from ectoderm cells along the sides of the neural tube

Question 19

3 regions of mesoderm

Answer 19

somites, intermediate mesoderm, lateral plate mesoderm

Question 20

somites

Answer 20

a series of paraxial mesoderm blocks found closest to the notochord, the first body segments

Question 21

paraxial

Answer 21

both sides of notochord

Question 22

intermediate mesoderm

Answer 22

lateral to the paraxial mesoderm, also segmented and attached to each somite

Question 23

lateral plate mesoderm

Answer 23

never divides into segments, begins as a single layer that quickly splits into two parts and encloses a space

Question 24

coelom cavity

Answer 24

divides lateral mesoderm layer into two layers: somatic mesoderm, splanchnic mesoderm

Question 25

somatic mesoderm

Answer 25

next to the ectoderm (outer)

Question 26

splanchnic mesoderm

Answer 26

next to endoderm (inner)

Question 27

somatic

Answer 27

think body wall

Question 28

splanchnic

Answer 28

something todo with the ...