Embryology Flashcards
the heart and great vessels come from what cell line?
the mesenchymal cells in the cardiogenic area
at what point do vasculogenesis and angiogenesis, blood vessel development begin?
at the beginning of the 3rd week
where does vasculogenesis and angiogenesis happen?
in the extraembryonic mesoderm of the yolk sac, allantosis and chorion
how does the heart tube form?
2 endothelial-lined channels, known as the endocardial heart tubes, fused together to form the heart tube
by the end of the 3rd week what does the primoridal CVS look like?
the heart is represented by the heart tubes and is joined by blood vessels from the embryo and extraembryonic membrane
What 4 main segments compose the inferior vena cava?
- hepatic segment; from the hepatic vein and sinusoids. 2. prerenal segment; from the right subcardinal veins. 3. renal segment; from the subcardinal supra anastomosis 4. post-renal; from the right supracardinal vein.
what germ layer forms the excretory organs?
mesoderm
what germ layer forms the glands opening into the GI tract?
endoderm
what germ layer forms the glandular cells o the liver and and pancreas?
endoderm
what germ layer forms the lining of the GI tract?
endoderm
what remnants persist after the joining of the embryonic palantine processes and is located in the soft palate>
the palantine raphe
the embryonic ductus venosus become what after birth?
ligamentum venosum
the embryonic umbilical vein become what after birth?
ligamentum teres
the embryonic umbilical arteries become what after birth?
umbilical ligament
from what does the aorta and pulmonary trunk develop?
a. bulbar ridges fuse and become an aorti-copulmonary septum. b. this then divides the bulbus cordis and the truncus arteriosis into two arterial channels. c. these two channels become the aorta and the pulmonary tree.
The aorta and the pulmonary truck are formed when in gestation
between week 5 and 6
At what point can a fetal heart beat be detected by a doppler heart monitor?
7 weeks after the last known menstrual period, aka 5 weeks in fertilization terms.
Fetal circulation happens in what order?
The umbilical vein delivers oxygenated blood. After bypassing the liver, the blood moves from the ductus venosus into the IVC and the right atrium. It enters the left atrium and ventricle through the foramen ovale. It enters the pulmonary trunk at the same time via the ductus arteriosis. After it enters the lung and the peripheral body through the aorta, it is passed back to the placenta thanks to the umbilical arteries.
The embryonic foramen ovale become what after birth?
fossa ovalis
the embryonic ductus arteriosis becomes what after birth?
ligamentum arteriosum
what forms the atria?
the separation into the right and left of the primitive sinuatrium or septum primum.
the fusion of the endocardial and atroventricular cushions posteriorly and anteriorly forms what?
the tricuspid and mitral inlets which become the AV valves.
what does the interventricular foramen result in?
by the end of week 7 it closes resulting in the interventricular septum.
from what tissue does the hypothalamus develop?
ectodermal tissue (on day 32 the hypothalamic sulcus develops from the diencephalon)
what tissue invaginates to form the anterior lobe of the pituitary gland? what is this known as?
Ectodermal tissue of the oropharynx, Known as: Rathke’s pouch (which eventually extends down to the HTH and becomes the pituitary stalk)
from what does the posterior lobe of the pituitary gland arise ?
neural crest
what does the pancreas form from?
two diverticular buds of the foregut
by what week have the first islet of the pancreas appeared?
around week 10, they first appear at the tail of pancreas
from what tissue does the thyroid develop?
its starts developing in the primitive ailmentary tract and consists of endodermal cells.
where does the thyroid first develop?
in the buccal cavity
what structure does the thyroid gland help to develop as it matures?
the tongue
what embryonic connection do the thyroid and tongue share?
the thyroglossal duct
where on the tongue does the thyroglossal duct open?
the foramen cecum
from which pouches do the parathyroid glands develop?
the superior glands descend from the 4th pharyngeal pouch and the inferior glands from the 3rd pharyngeal pouch.
True or false; the adrenal cortex and medulla develop from the same embryonic line?
false, the cortex develops from the coelomic mesodermal tissue and the medulla arises from the ectodermal tissue of the neural crest.
Between the adrenal cortex and the medulla, which develops parallel with the sympathetic nervous system?
the adrenal medulla
angioblasts from from what?
mesoderm
angioblasts form what as they cluster?
blood islands
the blood islands fuse together to form what?
a primordial vascular network
hemocytoblasts arise from what?
core cells within blood islands
blood formation occurs at what week?
week 5
what is the allantosis?
it is the part of the yolk sac that extends outward into the connecting stalk
what is the role of the allantosis?
it is involved in early blood formation, plays a role in bladder development, and its blood vessels become umbilical arteries and veins.
the liver starts hematopoesis during which week?
week 6
the fetal spleen takes over hematopoesis when?
week 26 to 28
from what does the thymus arise?
the 3rd pharyngeal pouch
what tissue forms the cortex and medulla of the thymus?
the cortex is formed from the ectoderm and the medulla is formed from the endoderm
the spleen arises from which germ line?
mesoderm
what are present in the spleen by the first trimester?
macrophages
True or false: the spleen is capable of hematopoiesis during fetal life
True, as well as after birth
what germ layer forms the bone marrow?
mesoderm
before bone marrow develops where are blood cells formed?
they start being produced in the yolk sac, then the liver takes over, and lastly the spleen handles the responsibility till the bone marrow matures.
what germ layer forms the connective tissue?
mesoderm
what germ layer forms the epidermis?
ectoderm
from what do the dermis and hypodermis arise?
mesoderm
how does the periderm develop?
ectodermal cells proliferate and forma layer of epithelium called periderm and a basal layer at the same time.
what happens to the peridermal cells?
the cells undergo kertinization and desquamation and are slowly replaced by other cells arising from the basale layer.