Part 2 Flashcards
As implantation progresses, the inner cell mass organizes into this.
Bilayer Embryonic Disc
The superficial layer of the bilayer embryonic disc consisting of high columnar cells related to the amniotic cavity.
Epiblast
The deep layer of the bilayer embryonic disc consisting of small cuboidal cells facing the blastocyst cavity.
Hypoblast
Formed during the first two to three weeks of development; lie outside the blastodisc and provide protection and nourishment for the embryo/fetus.
Extraembryonic Membranes
The first extraembryonic membrane to appear; participates in the formation of the gut and is the source of the earliest blood cells and blood vessels.
Yolk Sac
The “water bag”; formed when cells in the epiblast portion of the blastodisc migrate to line the inner surface of the amniotic cavity.
Amnion
The epiblast forms the floor of this.
Amniotic Cavity
By week 10, the amnion has mushroomed and envelops the embryo in a protective environment of this.
Amniotic Fluid
Cells from the yolk sac endoderm form a layer of connective tissue.
Extraembryonic Mesoderm
The outer extraembryonic membrane; formed by the cellular trophoblast and extraembryonic mesoderm.
Chorion
The extraembryonic coelom is called this when the chorion forms.
Chorionic Cavity
Extends from the chorion into the endometrial lacunae to establish the structural framework for the development of the placenta.
Chorionic Villi
Villi that grow more strongly on the former implantation pole.
Chorion Frondosum
Villi in other areas that decrease in number.
Chorion Laeve
Trophoblastic channels that allow maternal blood to percolate through.
Lacunae
Forms as a small out-pocketing of embryonic tissues at the caudal end of the yolk sac. Contributes the the structural base for the umbilical cord that links the embryo to the placenta and ultimately becomes part of the urinary bladder.
Allantois
The embryo is connected to the placenta by this.
Body Stalk
Where the yolk sac attaches to the endoderm of the embryo
Yolk Stalk
The yolk stalk and the body stalk together.
Umbilical Cord
Transport deoxygenated blood to the placenta
Umbilical Arteries
Return oxygenated blood to the embryo.
Umbilical Vein
Composed of inner epithelial endometrium and outer muscular myometrium.
Uterine Cavity
Area of the endometrium where the placenta is in contact.
Decidua Basalis
The rest of the endometrium where villi are absent; isolates the embryo from the uterine cavity.
Decidua Capsularis
The endometrium on the wall opposite to the embryo.
Decidua Parietalis
During week 3, cells begin to migrate. The bilaminar embryonic disc is converted into a trilaminar embryonic disc.
Gastrulation
The embryo during gastrulation.
Gastrula
Through the process of gastrulation, cells of the epiblast give rise to all three of these.
Germ Layers
The cells remaining in the epiblast form this.
Ectoderm
Some mesenchyme forms this.
Mesoderm
Cells from the epiblast further displace the hypoblast, forming this in the roof of the yolk sac.
Endoderm
Cells of the epiblast move toward the median place of the dorsal aspect of the blastodisc to this region.
Primitive Streak
A tissue consisting of loosely arranges cells suspended in a gelatinous matrix. Forms supporting tissues of the embryo.
Mesenchyme
The fourth to eighth weeks of the development constitute most of the embryonic period when all major external and internal structures are established.
Organogenesis
The three layers of the embryo folds form an internal cavity, which becomes the epithelial lining of the GI and respiratory tracts.
Primitive Gut
Segments of the primitive gut.
Foregut, Midgut, Hindgut
The foregut develops into 5 folds.
Pharyngeal Arches
The differentiation of ectoderm into brain and spinal cord.
Neurulation
The ectoderm at the cephalic end thickens and forms a neural plate that invaginates and pinches off, forming this.
Neural Tube
Parts of the neural tube.
Primary Vesicles
The three primary vesicles
Forebrain, Midbrain, Hindbrain
Two lateral outgrowths on each side of the forebrain. The primordia of the retinae and optic nerves.
Optic vesicle
Mesodermal cells beneath the early primitive streak aggregate, forming a rod of mesodermal cells. The first axial support of the embryo; is eventually replaced by the vertebral column.
Notochord
Paired cuboidal bodies that first appear in the future occipital region of the embryo, then soon develop craniocaudally to form sclerotomes, myotomes, and dermatomes, and give rise to most of the axial skeleton and associated musculature as well as the dermis of the skin.
Somite
Paired, longitudinal channels developed during the third week fuse to form this.
Heart Tube
Surrounds the heart tube.
Pericardium
Three vascular structures most important in the transitional circulation.
Ductus Arteriosus, Foramen Ovale, Ductus Venosus.
The right umbilical branch passes to the right side of the liver and is joined by this.
Portal Vein
Highly oxygenated, nutrient rich blood returns from the placenta via this.
Umbilical Vein
Returns blood to the placenta.
Umbilical Arteries
The left umbilical branch passes directly into the ductus venosus, which connects the umbilical vein to this.
Inferior Vena Cava
