LM 23: Embryology

Question 1

when does a zygote become a morula

Answer 1

1) at 64 cells

2) after cleavage

Question 2

Define compaction

Answer 2

1) morula cells compact together

2) cells begin to differentiate into trophoblast (outer) and embryoblasts (inner)

Question 3

what is a blastocyst

Answer 3

1) when morula embryoblasts compact to one side of trophoblastic ring forming ICM
2) creates a blastocoel (cavitation)
3) zona pellucida begins to fade away
4) begins 5 days after fertilization

Question 4

what happens during gastrulation

Answer 4

1) formation of 3 germ layers
2) epiblasts become ectoderm
3) hypoblasts become endoderm
4) formation of primitive streak which will cause conversion also leads to mesoderm

Question 5

what happens during neurulation

Answer 5

1) middle of mesoderm differentiates into the notochord
2) the notochord causes ectoderm above to form thickened neural plate
3) neural plate cells dive into mesoderm and forms a neural tube
4) some of neural plate ends up into mesoderm as neural crest cells (that will later specialize)

Question 6

Day 3 of early embryogenesis

Answer 6

8 cell zygote

Question 7

Day 6-7 of early embryogenesis

Answer 7

implantation of the blastocyst

Question 8

what happens during implantation

Answer 8

1) zona pellucida is shed and blastocyst attaches to uterus

Question 9

what is a malformation

Answer 9

1) intrinsic defects in genes

2) Greig cephalopolysyndactyly

Question 10

what is a deformation

Answer 10

1) caused by extrinsic factors impinging physically on fetus during development
2) common during 2nd trimester
3) arthrogryposes

Question 11

What are disruptions

Answer 11

1) destruction of irreplaceable normal fetal tissue