CP1 & CP2 - Embryology Handout notes Flashcards
apex of the heart
The lowest superficial part of the heart. It is directed downward, forward, and to the left, and is overlapped by the left lung and pleura. -wiki
relative position of the ventricles and atria
ventricles are anterior to atria
what is a summary of what the embryology of the heart builds?
the embryo will build a structure on the midline, with a posterior inflow tract for blood, a ventrally located pumping apparatus, and an outflow tract that is directed towards the head.
how do the morula and zygote get their nutrition.
from diffusion.
Where is the inner cell mass located in the embryo
Note the position of the inner cell mass is such that it is
located eccentrically within the sphere, close to the uterine wall.
how does the blastocyst implant into the endometrium?
what does the area become?
what is the name of the cells that do this?
where are their precursors?
Before the vascular system develops, the zygote implants into the endometrium and develops a syncytium from invasive, multinucleated trophoblastic cells.
what are the spaces that develop in the in the syncitium?
lacunae
Allantois
is a part of a developing amniote’s conceptus (which consists of all embryonic and extra-embryonic tissues). It helps the embryo exchange gases and handle liquid waste.
edge of the syncytiotrophoblast erodes into
some of the maternal blood vessels.
describe the lacunae.
On what day does blood begin to fill these structures? how does this happen?
These little lacunar spaces are somewhat interconnected. At 13-14 days post-fertilization, enough erosion will have occurred for maternal blood to flow from the maternal sinusoids into the lacunae, eventually filling them.
what are the blood vessels that are eroded by the syncytiotrophoblast called?
when does this occur?
what is the result of this?
- sinusoids
- At 13-14 days post-fertilization, enough erosion will have occurred for maternal blood to flow from the maternal sinusoids into the lacunae, eventually filling them.
Differential pressure levels in the lacunae will:
what is this called and what is an important characteristic?
When does this occur?
- cause blood to wash through the lacunae and back into maternal veins in the uterine wall.
- This is uteroplacental circulation – it is entirely maternal,
- beginning about 14 days after fertilization.
compare simple diffusion to uteroplacental circulation
-more efficient than simple diffusion, but it will not be good enough to support the development of the rapidly growing embryo.
HIgh resolution US suggests what about the rate of flow?
During what period?
-That rate of flow may be very low during the first 10 weeks of gestation; this remains a point of controversy.
what does the Embryonic circulatory system arise from?
In large part from the extraembryonic mesenchyme, where blood islands are forming.
How do cells form a vascular tree?
They clump together with the cells in the middle sloughing off to become blood cells, while the ones on the outside become the lining of the blood vessels. This is the beginning of a vascular tree
what is formation of blood vessels by formation of a vascular tree called?
what type of cells are formed? From what?
This type of vessel formation is vasculogenesis
-The differentiation of cells from the mesenchyme into both blood cells and endothelial cells
Where do the first blood vessels occur?
where else do they form?
blood islands form how long after that?
- The first blood vessels occur along the wall of the yolk sac.
- Some develop on the connecting stalk, as well as the allantois. These are all extraembryonic.
- Within a couple days, blood islands will also form in the embryo.
What happens in the embryo proper in the beginning of cardio embryology?
mesodermal cells ingress through the primitive streak some of them receive signals that determine them to become portions of the developing heart and circulatory system.
Cells that ingress near the cranial end of the primitive streak develop into
the outflow tract
Cells that ingress in mid-streak develop into
ventricle
Cells that ingress caudally develop into
atrium
As the cells ingress at different locations, there are areas of diff. conc. of what?
what does this do?
- retinoic acid concentrations,
- it primes them to receive inductive signals.
what is the source of the inductive signals?
what is this area a part of?
what is it close to?
- anterior visceral endoderm
- a specialized area of hypoblast near the caudal end of the presumptive prechordal plate.