Cardiac embryology Flashcards
How many hrs for a 2 cell stage cell to form?
30 hrs post fertilization
Sperm + oocyte =
Zygote (cell division)
How many hrs for a 4 stage cell to form?
40hrs post fertilization
How many hrs for a 12-16 cell stage to form?
72 hrs or 3 days post fertilization
Series of mitosis division in which cells increase in number and become smaller with each division is called what?
Blastomeres
Cells are loosely arranged until what cell stage?
8 cell stage
After the 3 rd cleavage, cells have maximized contact with each other and what occurs?
Compaction
Cells in compaction separate into what type of cells?
Inner and outer cells
16 stage cells is called what?
Morula
Inner cells =
Inner cell mass ( which will become the embryo)
Outer cell =
Outer cell mass (which become trophoblast which will become the placenta)
When the morula makes its way through the uterus and enlarges it become what?
Blastocyst (4 1/2 to 5 days post fertilization)
Fertilization occurs in what region of the Fallopian tube?
Ampullary region
When the morula enters the uterine cavity, fluid penetrates into the intercellular spaces of the inner cell mass and the spaces become now a single cavity called?
Blastocele
A blastocyst is comprised of?
1) Trophoblast 2) Blastocele and 3) embryoblast
What is the trophoblast?
Made of cells from outer mass cells. Cells flatten and form epithelial wall of blastocyst
Blastocele
Internal fluid filled space
Embryoblast
Inner cell mass. Located at one pole
Implantation occurs at around what day?
6th day after fertilization
At day 8, blastocyst is partially embedded and trophoblast differentiate into two layers?
syncytiotrophoblasts and cytotrophoblasts
Chorion
One of the fetal membranes (syncytiotrophoblasts and cytotrophoblasts make part of chorion)
Syncytiotrophoblasts
Multinucleated. Outer zone. No cell boundaries. Closer to endometrial than cytotrophoblasts.
Cytotrophoblasts
Mononucleated cells. Inner layer. Distinct cells
Inner cell mass (embryoblast) differentiates into?
Hypoblast and epiblast layers. endoderm and ectoderm respectively.
hypoblast layer?
Aka endoderm. Layer of small cuboidal cells adjacent to the blastocyst cavity
Epiblast layer?
Aka ectoderm. Layer of high columnar cells adjacent to the amniotic cavity
Day 11-12, syncytiotrophoblasts cells penetrate deep into endothelial lining of maternal capillaries. Capillaries are congested and dilated and are called?
Sinusoids
Sinusoids cause blood flow to trophoblastic system.
This is the beginning of uteroplacental circulation.
Cytotrophoblasts proliferate to form?
Amnion and amniotic cavity
Amnion
Thin protective membrane that surrounds the developing embryo
Amniotic cavity
Empty space which will eventually be filled with fluid
Gastrulation starts at what day?
8th day
Epiblast is the source for what?
The germ layers
Ectoderm
Skin, teeth, mouth glands, nervous system, some endocrine glands
Mesoderm
All connective tissue, the muscular, skeletal, lymphatic and circulation.
Endoderm
Epithelium of digestive tract, respiratory system, bladder, vagina and urethra
Cardiovascular system appears in the middle of the 3rd week
At this point embryo is not able to survive through diffusion. Vascular system develops from simple plexus and then into a complex vein and artery system. Size of embryo heart is enormous compared to embryo body’s vs adult heart and adult body
Day 16-18 progenitor heart cells lie in the epiblast.
Form a horse shoe cluster of cells called the primitive heart field.
Primitive heart field
Specified on both sides to become the atria, left and right ventricles, conus cordis and truncus arteriosus
Conus cordis and truncus arteriosus come from what field?
Secondary heart field and show up around day 20-21
Intraembryonic celom (body cavity)
Eventually become the pericardial cavity.
Angiogenic cells
Form blood islets
Blood islets form plexus which eventually develop into bilateral endocardial tubes.
Endocardial tube unit to form common tube which forms the primitive heart tube.
Day 21-22
The single heart tube begins to beat
If lengthening of heart tube doesn’t occur what defects develop?
DORT, VSD, TOF, PA AND PS
Formation of heart tube is essential formation of the RV, the conus cordis and the truncus arteriosus.
Yes
Heart tube day 23 heart tube begins to bend
Cephallic part bends ventrally, caudal and to the right.
caudal part bends dorsocrainally and to the left
Dorsal aorta and aortic sac
Becomes the common outflow tract
Bulbus cordis
Primitive right ventricle
Primitive ventricle
Primitive left ventricle
Atrioventricular sulcus
Divides atria from ventricle
Paired primitive atria
Gives rise to common atria
Sinus Venosus
Forms coronary sinus and oblique vein of the left atria
