Embryology Flashcards
What happens in the first week of embryology?
- Ovulation
- Fertilisation
- Implantation
What is ovulation?
- Egg released from ovaries and travels through fallopian tube
- Uterus prepares to receive egg - wall thickens
What is implantation?
fertilised egg attaches to wall of uterus
What is fertilised ovum called?
zygote (single cell)
What is a morula?
lump of cells formed at 4-6 days
(16 cells)
What is a blastocyst?
a hollow ball that has
a trophoblast
an inner cell mass (embryoblast)
formed at 6-10 days
What is the trophoblast?
A thin layer of cells that helps a developing embryo attach to the wall of the uterus, protects the embryo, and forms a part of the placenta.
What is the placenta?
organ that will organise the transport of nutrients to developing embryo and remove the waste from developing embryo
What positive factor can cause a rise of antibodies in the mother?
rhesus (Rh)
At approximately 10-12 days, the implanted trophoblast contains an embryoblast, which has 2 cell layers. (bilaminar embryo) What are the names of these layers?
epiblast
hypoblast
What does the epiblast give rise to?
embryonic ectoderm, mesoderm, endoderm
What does the hypoblast give rise to?
assists in formation of endoderm, extraembryonic (yolk sac) mesoderm
What does the embryo develop during gastrulation?
an axis (to become symmetrical)
the three cell layers (ectoderm, mesoderm, endoderm)
What is gastrulation?
Gastrulation is a key phase in embryonic development when pluripotent stem cells differentiate into the three primordial germ layers
What is the key stage of formation during gastrulation?
the formation of a groove which is the primitive streak
What is the primitive streak?
a linear band of thickened epiblast that first appears at the posterior end of the embryo and grows cranially
How do the three cell layers form?
Some ectodermal cells are induced to differentiate and migrate through the primitive streak, towards the hypoblast
These new cells are the mesoderm
An unknown interaction between the newly formed mesoderm and the hypoblast will form the endoderm