Embryogenesis

Question 1

Fertilization usually occurs in the ________ of the oviduct within 24hrs of ovulation

Answer 1

ampulla

Question 2

Series of cleave and differentiation events results in the formation of a __________ by the 4th embryonic day

Answer 2

blastocyst

Question 3

______________ of the blastocyst generates embryonic tissues

Answer 3

Inner cell mass (ICM)

Question 4

Outer ___________ of blastocyst generates placental tissues

Answer 4

trophectoderm

Question 5

____________ into the uterine wall occurs ~6th embryonic day (day 20 on menstrual cycle)

Answer 5

Implantation

Question 6

Clear zone of the egg, on the periphery

Answer 6

Zona pellucida

Question 7

Layer around the egg that provides nutrients

Larger and is easier to be captured by cilia to allow transport

Answer 7

Corona radiata

Question 8

______________ classify pregnancy as:
fertilization egad: moment of fertilization is d0
Division of pregnancy corresponding to development
Total gestation time = 38 weeks

Answer 8

Embryologists

Question 9

______________ classify pregnancy as:
Menstrual age: first day of menses is d0
Division of pregnancy into trimesters
Total gestation time = 40 weeks

Clinical time really two weeks later

Answer 9

Clinicians

Question 10

Sperm have _______ receptors

100s bind to the egg, but only one manages to contact the oollemma

Answer 10

ZP (zona pellucida)

Question 11

Fusion of sperm and egg membrane induces __________

Ca2+ influx and cortical reaction occur

Answer 11

Depolarization

Question 12

Cortical granules fuse with oollemma and release enzymes that digest ZP proteins so other sperm can no longer bind
Triggered by Ca2+ influx and depolarization
(hyaluronic acid and other proteoglycans are also released that become hydrated and swell, thus pushing the other sperm)

Answer 12

Cortical reaction

Question 13

Polar bodies are seen in the newly fertilized egg as evidence of:

Answer 13

meiosis (meiosis II not completed until fertilization)

Question 14

Successive splitting into smaller cells via mitosis (don’t grow cell size - just increase number of cells)
Goal: transform unicellular zygote into multicellular embryo

Answer 14

Cleavage

Question 15

During week 1, individual cells are called ___________ and are equivalent to each other (totipotent - can generate both embryo and placenta)

Answer 15

blastomeres

Question 16

Embryo undergoes _________ after 8-cell stage: first differentiation of embryonic lineages

Answer 16

compaction

Question 17

During compaction, there is increased cell-cell adhesion due to increased expression of ________ that allows segregation of cells

Answer 17

cadherin

Question 18

Cells that are forced to the outside of the compacted _________ are destined to become trophoblast (placenta) and the inner cells will form the embryo proper (ICM)

Answer 18

morula

Question 19

During formation of the blastocyst, fluid is pumped into the embryo for the cavitation of the embryo
The cavity is called then ____________

Answer 19

blastocoele

Question 20

During formation of the blastocyst, ________ channels appear on the surface of the outer trophoblast cells
Sodium and water are pumped into the forming blastocoele (embryo still contained in zone pellucida)

Answer 20

sodium

Question 21

Hatching of the embryo from the zone pellucida occurs just prior to __________

Answer 21

implantation

Question 22

Inability to hatch from ___________ in preparation for implantation results in infertility, and premature hatching can result in abnormal implantation in uterine tube

Answer 22

zona pellucida

Question 23

Implantation somewhere other than upper portion of uterus

Rupture can lead to life-threatening hemorrhage

Answer 23

Ectopic pregnancy

Question 24

Ectopic pregnancies typically occur in the __________ region

Answer 24

ampullary

Question 25

During week 2 (implantation), a ___________ embryo develops, along with the amniotic cavity and yolk sac

Answer 25

bi-laminar

Question 26

During implantation and placentation, the trophoblast differentiates into _______________, which is the stem cell population

Answer 26

Cytotrophoblast

Question 27

During implantation and placentation, the trophoblast differentiates into _______________, which is invasive fused cells (syncytium -multi-nuclei) derived from the cytotrophoblast

Answer 27

Syncytiotrophoblast

Question 28

During implantation and placentation, the trophoblast differentiates and breaks maternal capillaries, causing trophoblastic ________ to fill with maternal blood

Answer 28

lacunae

Question 29

During implantation and placentation, the inner cell mass divides into:

Answer 29

Epiblast

Hypoblast

Question 30

The ________ derived from ICM contributes to forming the overlying amniotic membrane and amniotic cavity
(all embryonic structure - dorsal)

Answer 30

Epiblast

Question 31

The _________ derived from ICM contributes to forming the underlying yolk sac (ventral)

Answer 31

Hypoblast

Question 32

The _____________ derived from the trophoblast invades maternal tissues by hitting maternal blood vessels, blood spills in, fusion of maternal and fetal blood (diffusion, not direct mixing)
Substances can cross (before mother knows she is pregnant - alcohol, etc.)

Answer 32

Syncytiotrophoblast

Question 33

The _________ allows for exchange (not mixing) between maternal and fetal blood

Answer 33

placenta

Question 34

Early placental barrier (1-12 weeks) has more layers:

Answer 34

Syncytium
Cytotrophoblast
Embryonic CT
Endothelium

Question 35

Later placental barrier (4th month - term) has fewer layers:

Answer 35

Syncytium

Endothelium