W2 Early Embryology Flashcards
Fertilization, cleavage, ___ occurs during __ week of fetal development.
Implantation, 1st
Second week is the week of 2:
Bilaminar disc, two sacs, two __
two trophoblast layers
Gastrulation and formation of 3 germ layers occur during __ week of development.
3rd
Twinning occurs during __ week of development.
3rd
Cell differentiation is induced by group of cells called __ __ during __ week of development.
organizing centers, 3rd
During cleavage, cells are __. They cells give rise to all cells.
totipotent (including placenta)
What are the components of blastocyst?
ICM
Trophoblast
Blastocoel
IMC (embryoblast) give rise to ___ and trophoblast give rise to ___.
Embryo, placenta
Define pluripotent embryonic stem (ES) cells.
Give rise to all adult tissues (including germ cells, but except placenta)
Totipotent
Pluripotent
Compare and contrast
Both stem cells but pluripotent can’t give rise to placenta
Embryonic stem cells are pluripotent/totipotent
pluripotent
What type of cell is the endometrium?
Uterine epithelium
What facilitates the attachment of blastocyst to the endometrium?
Secretion of enzymes from the trophoblast
ICM is totipotent/pluripotent embryonic cell
pluripotent
Where do germ cells come from?
ICM; it’s where all adult body cells come from
Trophoblast differentiates into two layers. What are they and their functions?
Cytotrophoblast - cells divide, fuse
Synctiotrophoblast - secrete HCG (multinucleated)
ICM also differentiates into two types of epithelia cells. What are they?
Columnar Epiblast
Cuboidal Hypoblast
Where does fertilization occur? Implantation?
Fallopian tube, uterus
How many granulosa cells are needed for ovulation? Why?
30-40 cells; enough estrogen will be secreted
What hormone causes release of oocyte from the follicle? What is this process called?
LH; ovulation
What becomes of the follicle post ovulation?
Some are attached to the released oocyte (corona radiata)
Most remain in the ovary and form the corpus luteum, secreting progesterone
Granulosa cells secrete ___. Corpus luteum secrete ___.
Estrogen, progesterone
Follicle consists of __ and __.
Oocyte, granulosa cells
How long is fertility period for women?
Oocyte available for up to a day
Sperm - quiescent for up to 6 days
Fertility period for woman - 7 days
If no fertilization occurs, corpus luteum degenerates after __ days into the menstrual phase.
28
HCG has the same effect as hormone __
LH
During menstruation, LH sustains corpus luteum. During pregnancy, ___ takes over.
HCG
RU-468 is a ___ receptor inhibitor that induces abortion.
Progesterone (produced from corpus luteum)
Why is week 2 called week of twos?
2 epithelial bilaminar disc (epiblast, hypoblast)
2 cavities
2 layers of trophoblast (cytotrophoblast, syncytiotrophoblast)
Where is the amniotic cavity and what is its function?
In the epiblast; it encloses the embryo; when water breaks, fluid is from this cavity
ICM (epiblast, hypoblast)
trophoblast (cytotrophoblast, syncytiotrophoblast)
Which one contributes to the embryo?
Only epiblast
During what period of fetal development can conjoined twins arise?
3rd week: gastrulation
Cells in the dorsal lip of a frog is analogous to __ __ in humans. They induce differentiation of neighboring cells.
Organizing centers (primitive node)
As epiblast cells reach primitive streak, they undergo __.
EMT (epithelial mesenchymal transition)
In fetal developmental EMT, epiblast at the primitive streak become ___, ___ stem cell.
Migratory, multipotent
Mesoderm organization during invagination (gastrulation): axial (notochord) paraxial (\_\_) intermediate (\_\_) lateral plate extra embryonic
axial (notochord) paraxial (somite) intermediate (kideny) lateral plate extra embryonic
Mermaid limbs (aka __, __ __) happens when lack of ventral mesoderm in the posterior primitive streak causes lower limbs to fuse.
Sirenomelia, caudal dysgenensis
What are the three ways identity twins can arise?
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)
Rarely, twins can arise when there is division at ___ stage, resulting in 2 placenta and 2 amniotic cavity.
Morula
The most common way identical twins arise is when __ splits into two, resulting in __ placenta and __ amniotic cavity.
ICM, 1, 2 (only share placenta)
Siamese twins may arise when two ___ ___ arise, resulting in __ placenta and __ amniotic cavity.
Primitive streaks, 1, 1 (share all)
Blastocyst contains __ stem cells
embryonic (pluripotent)
__ directs physiology of the mother via secretion of __
trophoblast, HCG
entire adult body is derived from __ of ICM.
epiblast
