Embryology Exam Review Powerpoint

Question 1

Timeline day 0 (embryonic age)

Answer 1

• Day 0 is fertilization forming a zygote in distal third of fallopian tube
• Division into morula (ball of cells will become placenta and embryo, each cell is totipotential)
• Division into blastocyst (blastocele (cavity) containing embryoblast, trophoblast at other pole form placenta)

Question 2

Timeline week 1 (embryonic age)

Answer 2

-up to week 1 implantation on uterine wall of blastocyst

Question 3

“I was drinking when I believe I conceived, did I harm the baby?”

Answer 3

First 3 weeks -“All or nothing” insult or damage to fetus at this time will cause miscarriage immediately or no damage

Question 4

Timeline week 2 (embryonic age)

Answer 4

• Bilaminar disk formation, evolution of embryoblast to bilaminar blastocyst with cell layers epiblast and hypoblast (primitive ecto and endoderms) sandwiched between 2 cavities - amniotic cavity and yolk sac
• Trophoblast divides into cystotrophoblast (inner single cell layered) and syncytiotrophoblast (thicker outer layer releases hGC to prevent menstruation)

Question 5

“I just missed my period, what is embryonic age and gestational age?”

Answer 5

Week 2 embryonic age, week 4 gestational age

Question 6

Zygote

Answer 6

Union between sperm and egg, quickly begins divisions into morula

Question 7

Morula

Answer 7

Ball of cells that will become placenta and embryo, divided from a zygote, each cell is totipotential

Question 8

Blastocele

Answer 8

Part of a blastocyst, fluid filled cavity that forms from a morula and will house an embryoblast

Question 9

Embryoblast

Answer 9

Part of a blastocyst, early embryo formed from a morula and contained in a blastocele

Question 10

Trophoblast

Answer 10

Part of a blastocyst, early placenta formed from a morula surrounding a blastocele

Question 11

Blastocyst

Answer 11

Continuation from a morula, houses a blastocele containing an embryoblast, and a trophoblast layer of cells surounding

Question 12

Bilaminar blastocyst

Answer 12

Continuation from blastocyst contains inner hypoblast and outer epiblast layers out of the embryoblast

Question 13

Amniotic cavity

Answer 13

Forms around the epiblast to create a fluid filled cavity to house the embryoblast in a bilaminar blastocyst

Question 14

Yolk sac

Answer 14

Forms extending out of the hypoblast to eventually give rise to the umbilical cord in a bilaminar blastocyst

Question 15

Cystotrophoblast

Answer 15

Division from the trophoblast into a single inner cell layer in a bilaminar blastocyst, will be important for implantation

Question 16

Snynctiotrophoblast

Answer 16

Division from the trophoblast into a thick outer cell layer in the bilaminar blastocyst, releases hCG to maintain high progesterone levels in the mother to prevent menstruation and maintain pregnancy

Question 17

What occurs in week 3-8 (embryonic age) and why is this the most susceptible time?

Answer 17

-Organogenesis occurs, most susceptible because 90% of birth defects will occur here

Question 18

Timeline week 3(embryonic age)

Answer 18

• Gastrulation (transition from blastocyst to a gastrula)
• Primitive streak (structure forming posterior side, determines site of gastrulation and bilateral symmetry), notochord (becomes nucleus pulposis of intevertebral disks), and neural plate (basis for nervous system) form here, as well as division of the hypo/epiblasts into ecto/meso/endoderms

Question 19

Gastrulation

Answer 19

Transition of a blastocyst into a multilayered gastrula

Question 20

Primitive streak

Answer 20

Stucture of the gastrula forming posterior side that determines site of gastrulation and creates bilateral symmetry

Question 21

Notochord

Answer 21

Structure of the gastrula forming nucleus pulposis of intervertebral disks

Question 22

Neural plate

Answer 22

Structure of gastrula forming nervous system basis (and dermatome distribution)

Question 23

Ecto/meso/endoderm form…

Answer 23

• Ecto forms epithelium and nervous system
• Meso forms bone, muscle, cartilage, blood
• Endo forms excretory strutures, GI, respiratory, urinary

Question 24

Folate deficiency at week 3 (embryonic age) can cause this developmental disorder

Answer 24

Spinal bifida upon neural plate formation

Question 25

Timeline week 4 (embryonic age)

Answer 25

• Heartbeat, 4 chambers, 4 limb buds, 4 branchial arches (gill like structures that give rise to features of the head and neck)
• tongue lungs GI and diaphragm development too

Question 26

Critical period for autism spectrum disorder, ventricular septal defect, and tricuspid atresia

Answer 26

Week 4-6 (embryonic age)

Question 27

Critical period for limb defect

Answer 27

Week 4-5 (embryonic age)

Question 28

Critical period for cleft lip defect

Answer 28

Week 5-6 (embryonic age)

Question 29

Timeline weeks 5-7 (embryonic age)

Answer 29

-gonad differentiation, kidney, bladder, rectum formation

Question 30

Critical period for teeth/palate

Answer 30

Week 6-7 (embryonic age)

Question 31

Timeline week 8 (embronic age)

Answer 31

fetal movement, strong resemblance to baby

Question 32

Critical period for external genitalia formation

Answer 32

Week 8 (embryonic age)

Question 33

At what time can you tell the sex of the fetus?

Answer 33

Week 10 (embryonic age)