Embryology 4 (final) Flashcards
Spaces form in the lateral intraembryonic mesoderm and cardiogenic mesoderm. These spaces are called ________________ spaces. These are the start of the intraembryonic coelom (embryonic body cavity)
coelomic
The coelomic vesicles subsequently fuse together (coalesce) to form a single, horse-shoe-shaped cavity that eventually gives rise to…
body cavities
Embryonic nutrition is obtained from the maternal blood by diffusion through the….
extraembryonic coelom and umbilical vesicle
In the 3rd week, blood vessel formation begins in the extraembryonic mesoderm of the….
umbilical vesicle, connecting stalk, and chorion (embryonic blood vessels begin to develop 2 days later)
The early formation of the cardiovascular system is correlated with the urgent need for blood vessels to bring oxygen and nourishment to the embryo from the maternal circulation through the…
placenta
The formation of the embryonic vascular system involves 2 processes. What are they?
vasculogenesis and angiogenesis
________________ is the formation of new vascular channels by the assembly of individual cell precursors (angioblasts make vessels)
vasculogenesis
_________________ is the formation of new vessels by budding and branching from pre-existing vessels
angiogenesis
Blood vessel formation in the embryo and extraembryonic membranes during the 3rd weeks begins when mesenchymal cells (within the mesoderm) differentiate into endothelial cell precursors, aka…
angioblasts
Blood vessels develop from specialized endothelial cells of vessels as they grow on the ___________________ and allantois at the end of the 3rd week
umbilical vesicle (source of RBCs/WBCs)
The heart and great vessels form from mesenchymal cells in the….
cardiogenic mesoderm/area
Paired endocardial heart tubes, develop during the 3rd week and fuse to form a…..
primordial heart tube
The tubular heart joins with blood vessels in the embryo, connecting the stalk, chorion, and umbilical vesicle to form a….
primordial cardiovascular system
The GI tract is the main organ system derived from the ______________ germ layer
endodermal
Which germ layer covers the ventral surface of the embryo and forms the roof of the yolk sac?
endoderm
Lengthening of the ________________, causes the embryo to curve into a fetal position as the head and tail regions (folds) moves laterally. As the head an tail and 2 lateral folds move ventrally, they pull the amnion down with them, such that the embryo lies within the amniotic cavity
neural tube
A significant event in the establishment of body form is folding of the flat trilaminar embryonic disc into a somewhat cylindric embryo. The embryonic disc undergoes a process of folding that creates the basic vertebrate body form, called the tube-within-a-tube body plan. A major force responsible for embryonic folding in the differential growth of different portions of the embryo. Folding occurs in the _________ and ___________ planes and results from the rapid growth of the embryo. The growth rate at the sides of the embryonic disc fails to keep pace with the rate of the growth in the long axis as the embryo increases rapidly in length. Folding at the cranial and caudal ends and sides of the embryo occurs simultaneously
median, horizontal
As the embryo grows rapidly, particularly in length, it undergoes a process of folding that generates the recognizable vertebrate body form. During the 4th week, the embryonic disc and the amnion grow vigorously, but the _____________ hardly grows at all. Bc the yolk sac is attached to the ventral rim of the embryonic disc, the differential expansion is thought to drive the ballooning of the embryonic disc in a 3D cylindrical shape.
yolk sac
Where is most of the body folding concentrated in?
thin, flexible outer rim of the embryonic disc
The cranial, caudal, and lateral margins of the disc fold completely under the dorsal axial structures and give rise to the….
ventral surface of the body
The cranial, caudal, and lateral margins of the disc fold completely under the dorsal axial structures and give rise to the ventral surface of the body. Even though the 3 folds have different names, they become continuous with one another as a ring of tissue at the position of the future ______________
umbilicus (belly button)
The _____________ of the original embryonic disc covers the entire surface of the 3D embryo except for the future umbilical region, where the yolk sac and the connecting stalk emerge
ectoderm
An embryo body design is composed of 2 main tubes, an outer ectodermal tube forming the external layer of the _________________, an inner endodermal tube forming the inner layer of the _______. The space between the 2 tubes is filled mainly with mesoderm, the lateral plate mesodermal part of which splits to form the body cavity/coelom
skin (epidermis), gut
After the neural tube forms, it becomes subdivided in the cranial-caudal axis into forebrain, midbrain, and hindbrain, and the ______________
spinal cord
Neural crest cells are a unique population of cells that arise from the ________ part of the forming neural tube during neurulation. Neural crest cells migrate from the tube and become many structures including the _______________
dorsal, entire PNS
At the end of the 3rd week, the neural tube is elevating and closing _____________, whereas the git tube is rolling and closing ___________ to create a “tube on top of a tube”
dorsally, ventrally
Mesoderm holds the neural and gut tube together and the lateral plate mesoderm splits to form a visceral (____________) layer associated with the gut and parietal (___________) layer that, together with overlying ectoderm, forms the lateral body wall folds
splanchnic, somatic
The space between the visceral and parietal layers of lateral plate mesoderm is the….
primitive body cavity
The _______________ starts as continuous bilateral clumps of cells as the neural tube closes
neural crest
What does the neural crest form into?
test q!
-entire PNS
-sensory and autonomic ganglia
-Schwann cells (glial cells)
-adrenal medulla
-melanocytes
they also move into the head and form the
-bones of the skull
-smooth m
-lens
-anterior pituitary
-ganglia of CN V, VII, IX, and X
What are the 2 main embryo regions?
head (CNS level differentiates first, mesencephalic region of neural folds)
body (spinal cord level, lateral edges of fused neural tube)
