Bilaminer Disc & Endometrium Implantation

Question 1

Week 2

Answer 1

Bilaminer disc and endometrium implantation

Question 2

Review of blastula

Answer 2

• Day 5
• hallow ball of cells
• Morula (SOILD ball) becomes Blastula (HALLOW ball)
• Rapid series of mitotic cell divisions results in daughter Blastomeres
• By Day 6: About 100 cells
• AKA: Blastoderm or blastodisc around a space called the Blastocoel

ICM: embryo
Trophoblast: placenta

Question 3

What is the purpose of the Bilaminer Disc?

Answer 3

• Need to set up the organization of the embryo and extraembryonic membranes
• prep for implantation into uterus
• ICM (embryoblast) gives rise to 2 layered structures (epiblast and hypoblast)
• these two layers together are flanked by the amniotic cavity and yolk sac

Question 4

What are the two layered structures the embryoblast gives rise to?

Answer 4

1.) Epiblast
2.) Hypoblast

Question 5

ICM is also called

Answer 5

• Bilaminer disc
• the primitive endoderm

Question 6

4 extraembryonic membranes

Answer 6

• protect and manage nutrients and wastes:
  1.) Chorion– vessels
  2.) Amnion– sac and fluids
  3.) Allantois– wastes
  4.) Yolk sac– nutrients

Question 7

Waste removal is taken over by the______

Answer 7

umbilical cord

Question 8

Movement of cells and cavities

Answer 8

cells need to differentiate and replicate

Question 9

ICM called the _________

Answer 9

Bilaminer disc

Question 10

ICM differentiates further into

Answer 10

1.) Epiblast (dorsal)
2.) Hypoblast (ventral)

Question 11

Bilaminer disc forms

Answer 11

• embryo proper (fetus)
• extraembryonic membranes

Question 12

The bilaminer disc splits the sphere to make TWO cavities

Answer 12

1.) Amniotic
2.) Chorionic/Blastocyst

Question 13

ICM into Epiblast into what?

Answer 13

• into the 3 germ layers
• Allantois
• Amnion

Question 14

ICM into Hypoblast into what?

Answer 14

• into Chorion
• Yolk sac
• does NOT become embryo

Question 15

Amniotic cavity develops between__________ and __________

Answer 15

Trophoblast; Epiblast

Question 16

Amniotic cavity

Answer 16

a thin layer of cells from epiblast surrounds the amniotic cavity to become the AMNION

Question 17

Syncytio-tropho-blast (STB) (together-nourish-cells)

Answer 17

• the outer syncytial layer of the trophoblast that actively invades the uterine wall forming the outermost fetal component of the placenta
• *Nutrient and waste exchange
• Hormone synthesis
• *STB produces human chorionic gonadotropin (hCG), a hormone that stimulates the corpus luteum to produce progesterone, which helps maintain the pregnancy
• *Protein and lipid metabolism
• *Anti-angiogenic factors
• *In preeclampsia, a major cause of maternal mortality and morbidity, the release of syncytial factors increases

Question 18

Cyto-tropho-blast (cells-nourish-cells)

Answer 18

• a tissue of specialized cells in the placenta that lines the cavity and extends into the syncytiotrophoblast
• *Invade the uterus and replace maternal cells that line uterine vessels; this allows them to divert maternal blood to the placenta
• give rise to the plasmodial syncytiotrophoblast, which covers the placental villi *“Development”
• *highly metabolically active and contribute to global metabolism in the placenta
• *generate lipid droplets containing triglycerides and other lipid species
• *also involved in preeclampsia- associated with shallow cytotrophoblast invasion, which can lead to decreased blood flow to the fetus

Question 19

The hypoblast cell number increases from Day 8-12

Answer 19

Hypoblast cells sends out 2 waves of endodermal cells into blastocoel

Question 20

1st wave

Answer 20

makes primary yolk sac

Question 21

2nd wave

Answer 21

transforms 1 degree yolk sac into a 2 degree yolk sac

Question 22

Chorion cavity

Answer 22

develops between trophoblast, outer amnion, and yolk sac from new extraembryonic mesodermal cells

Question 23

On days 11-13

Answer 23

Mother’s blood vessels move in

Question 24

Mammal gastrulation is similar to_____

Answer 24

birds

Question 25

The embryo is now a germ disc with:

Answer 25

• upper layer epiblast
• lower layer hypoblast

Question 26

ICM epiblast delaminates, forming what?

Answer 26

1.) Amniotic cavity
2.) Amnion
3.) Amnionic cavity (at embryonic pole)

Question 27

Hypoblast forms what?

Answer 27

1.) Yolk sac
2.) Chorion

Question 28

Epiblast cells will migrate through a _________ ________ forming embryonic primitive ________ and _________

Answer 28

Primitive Streak; Endoderm; Mesoderm