W2 Early Embryology

Question 1

Fertilization, cleavage, ___ occurs during __ week of fetal development.

Answer 1

Implantation, 1st

Question 2

Second week is the week of 2:

Bilaminar disc, two sacs, two __

Answer 2

two trophoblast layers

Question 3

Gastrulation and formation of 3 germ layers occur during __ week of development.

Answer 3

3rd

Question 4

Twinning occurs during __ week of development.

Answer 4

3rd

Question 5

Cell differentiation is induced by group of cells called __ __ during __ week of development.

Answer 5

organizing centers, 3rd

Question 6

During cleavage, cells are __. They cells give rise to all cells.

Answer 6

totipotent (including placenta)

Question 7

What are the components of blastocyst?

Answer 7

ICM
Trophoblast
Blastocoel

Question 8

IMC (embryoblast) give rise to ___ and trophoblast give rise to ___.

Answer 8

Embryo, placenta

Question 9

Define pluripotent embryonic stem (ES) cells.

Answer 9

Give rise to all adult tissues (including germ cells, but except placenta)

Question 10

Totipotent
Pluripotent
Compare and contrast

Answer 10

Both stem cells but pluripotent can’t give rise to placenta

Question 11

Embryonic stem cells are pluripotent/totipotent

Answer 11

pluripotent

Question 12

What type of cell is the endometrium?

Answer 12

Uterine epithelium

Question 13

What facilitates the attachment of blastocyst to the endometrium?

Answer 13

Secretion of enzymes from the trophoblast

Question 14

ICM is totipotent/pluripotent embryonic cell

Answer 14

pluripotent

Question 15

Where do germ cells come from?

Answer 15

ICM; it’s where all adult body cells come from

Question 16

Trophoblast differentiates into two layers. What are they and their functions?

Answer 16

Cytotrophoblast - cells divide, fuse

Synctiotrophoblast - secrete HCG (multinucleated)

Question 17

ICM also differentiates into two types of epithelia cells. What are they?

Answer 17

Columnar Epiblast

Cuboidal Hypoblast

Question 18

Where does fertilization occur? Implantation?

Answer 18

Fallopian tube, uterus

Question 19

How many granulosa cells are needed for ovulation? Why?

Answer 19

30-40 cells; enough estrogen will be secreted

Question 20

What hormone causes release of oocyte from the follicle? What is this process called?

Answer 20

LH; ovulation

Question 21

What becomes of the follicle post ovulation?

Answer 21

Some are attached to the released oocyte (corona radiata)

Most remain in the ovary and form the corpus luteum, secreting progesterone

Question 22

Granulosa cells secrete ___. Corpus luteum secrete ___.

Answer 22

Estrogen, progesterone

Question 23

Follicle consists of __ and __.

Answer 23

Oocyte, granulosa cells

Question 24

How long is fertility period for women?

Answer 24

Oocyte available for up to a day
Sperm - quiescent for up to 6 days

Fertility period for woman - 7 days

Question 25

If no fertilization occurs, corpus luteum degenerates after __ days into the menstrual phase.

Answer 25

28

Question 26

HCG has the same effect as hormone __

Answer 26

LH

Question 27

During menstruation, LH sustains corpus luteum. During pregnancy, ___ takes over.

Answer 27

HCG

Question 28

RU-468 is a ___ receptor inhibitor that induces abortion.

Answer 28

Progesterone (produced from corpus luteum)

Question 29

Why is week 2 called week of twos?

Answer 29

2 epithelial bilaminar disc (epiblast, hypoblast)

2 cavities

2 layers of trophoblast (cytotrophoblast, syncytiotrophoblast)

Question 30

Where is the amniotic cavity and what is its function?

Answer 30

In the epiblast; it encloses the embryo; when water breaks, fluid is from this cavity

Question 31

ICM (epiblast, hypoblast)
trophoblast (cytotrophoblast, syncytiotrophoblast)
Which one contributes to the embryo?

Answer 31

Only epiblast

Question 32

During what period of fetal development can conjoined twins arise?

Answer 32

3rd week: gastrulation

Question 33

Cells in the dorsal lip of a frog is analogous to __ __ in humans. They induce differentiation of neighboring cells.

Answer 33

Organizing centers (primitive node)

Question 34

As epiblast cells reach primitive streak, they undergo __.

Answer 34

EMT (epithelial mesenchymal transition)

Question 35

In fetal developmental EMT, epiblast at the primitive streak become ___, ___ stem cell.

Answer 35

Migratory, multipotent

Question 36

Mesoderm organization during invagination (gastrulation):
axial (notochord)
paraxial (\_\_)
intermediate (\_\_)
lateral plate
extra embryonic

Answer 36

axial (notochord)
paraxial (somite)
intermediate (kideny)
lateral plate
extra embryonic

Question 37

Mermaid limbs (aka __, __ __) happens when lack of ventral mesoderm in the posterior primitive streak causes lower limbs to fuse.

Answer 37

Sirenomelia, caudal dysgenensis

Question 38

What are the three ways identity twins can arise?

Answer 38

split at morula stage, ICM splits, two primitive streaks arise

1) Embryo divide before “morula” stage (rare); can’t tell if it’s fraternal or identical
Two placenta, two amniotic cavities

2) Most common way; blastocyst has “ICM” split into two
one placenta, two amniotic cavities (only shared placenta)

3) One ICM, “two primitive streak”/primitive organizers or primitive nodes; may give rise to Siamese twins if embryos don’t separate completely
One placenta, one amniotic cavities (share all)

Question 39

Rarely, twins can arise when there is division at ___ stage, resulting in 2 placenta and 2 amniotic cavity.

Answer 39

Morula

Question 40

The most common way identical twins arise is when __ splits into two, resulting in __ placenta and __ amniotic cavity.

Answer 40

ICM, 1, 2 (only share placenta)

Question 41

Siamese twins may arise when two ___ ___ arise, resulting in __ placenta and __ amniotic cavity.

Answer 41

Primitive streaks, 1, 1 (share all)

Question 42

Blastocyst contains __ stem cells

Answer 42

embryonic (pluripotent)

Question 43

__ directs physiology of the mother via secretion of __

Answer 43

trophoblast, HCG

Question 44

entire adult body is derived from __ of ICM.

Answer 44

epiblast