Lecture 11 (Exam 2) Flashcards
The initial signaling for endoderm formation occurs during…
Gastrulation
Signaling for endoderm formation depends on _______ expression during gastrulation.
Nodal
Signaling for endoderm formation during gastrulation contains an anterior-posterior gradient. There are higher levels of nodal (ANTERIORLY/POSTERIORLY) and lower levels of nodal plus the presence of FGF-4 (ANTERIORLY/POSTERIORLY).
Anteriorly
Posteriorly
The posterior gut expresses ______. This promotes hindgut development and suppresses formation of anterior gut structures.
Cdx-2
The anterior gut expresses…
Hex
Sox-2
Foxa-2
More refined differentiation of gut structures depends on _____ genes.
Hox
In the anterior intestinal portal, there is an expression of…
Shh
In the posterior intestinal portal, there is an expression of _____ followed by _____.
Shh
BMP-4
Both the __________ membrane and ________ plate are formed by endoderm and ectoderm with no intervening mesoderm. Instability created by lack of mesoderm results in perforations of these plates.
Oropharyngeal (Oral plate)
Cloacal
There are pockets created on the ectodermal sides of the oral and cloacal plates. The _________ is the future oral cavity, and the _________ is the future anal region.
Stomodeum
Proctodeum
During this week of the embryo, the length is 4 mm. Rudiments for most of the major organ systems are present (except limbs and kidneys). There are prominent pharyngeal arches and a Wolffian ridge.
4th week
This extraembyronic tissue is part of the inner cell mass and an epiblast derivative.
Amnion
This extraembryonic tissue is part of the inner cell mass and a hypoblast derivative.
Yolk sac
These extraembryonic tissues are part of the fetal maternal interface and are trophoblast derivatives.
Chorion
Placenta
This extraembryonic tissue is part of the inner cell mass and interfaces with placenta via the umbilical cord.
Allantois
The function of this extraembryonic tissue to accommodate growth, allow normal movements, buffer against mechanical injury, and protect the fetus from adhesions.
Amnion
What is the normal amount of amniotic fluid at term?
500-1000 mL
This is the term for an excess amount of amniotic fluid (>2000 mL). It is related to multiple pregnancies, esophageal atresia (swallowing defects), and anencephaly (head defects).
Hydramnios
This is the term for too little amniotic fluid (<500 mL). It is related to renal agenesis (absence of kidneys) and shows the importance of fetal urine contributions.
Oligohydramnios
In phase I of the formation of amniotic fluid –
- First _____ weeks of pregnancy
- Free diffusion of _______ through fetal ectoderm
- Maternal serum
- Secretion by amniotic membrane
20
Electrolytes
In phase II of the formation of amniotic fluid –
- Contributions from fetal ______
- Filtration from vessels associated with _____ _____
Urine
Chorion laevae
What nutrients are concentrated in the yolk sac?
Folic acid
Vitamin A
Vitamin B12
Vitamin E
This is the term used for when nutrients are concentrated in the yolk sac and absorbed by endocytosis before the placental circulation is established.
Histiotrophic nutrition
The yolk sac is also the site of origin of ______ ______ cells and is the location of ______ ______, which are the origin of initial blood cells (extraembryonic hematopoiesis).
Primordial germ
Blood islands
In a small percentage of adults, they contain traces of the yolk duct as a fibrous cord or outpouching of the small intestine. This is called…
Meckel’s diverticulum
The allantoic (_______) vessels develop in the mesoderm of the allantois.
Umbilical
The proximal part of the allantois is called the _______. It is associated with the formation of the urinary bladder and becomes the _______ _______ ligament.
Urachus
Median umbilical
In this stage of placental development, there are no villi formed on the trophoblast.
Previllous embryo
In this stage of placental development, solid, cytotrophoblastic, ectodermal primary villi appear.
Primary villous stage
In this stage of placental development, the mesodermal core appears within the primary villi.
Secondary villous stage
In this stage of placental development, it is characterized by the appearance of blood vessels within the mesenchymal core of the secondary villi.
Tertiary villous stage
In the final stages in development of the placenta, there are cytotrophoblastic (SHELLS/COLUMNS) which go on to expand over the maternal decidual cells and form cytotrophoblastic (SHELLS/COLUMNS).
Columns
Shells
In the final stages in development of the placenta, there are ________ villi which are anchored to the cytotrophoblastic shell (as opposed to floating villi).
Anchoring
In the maternal blood flow pathway, the maternal blood enters intervillous spaces, called ________ _______, from _______ arteries.
Trophoblastic lacunae
Spiral
In the maternal blood flow pathway, there is an exchange of materials (respiratory gasses, nutrients, waste products) between maternal blood in lacunae and fetal blood in ________ in the villi.
Capillaries
In the maternal blood flow pathway, the maternal blood returns to maternal veins in the _______ _______.
Decidua basalis
In the fetal blood flow pathway, fetal blood is entirely enclosed within _______.
Vessels
In the fetal blood flow pathway, fetal blood travels to capillary beds within placental villi via ________ arteries (usually two).
Umbilical
In the fetal blood flow pathway, fetal blood returns from capillary beds within placental villi via ________ vein (usually one).
Umbilical
In the maternal-fetal blood flow pattern, there is usually (ONE/TWO) umbilical artery(ies), and (ONE/TWO) umbilical vein(s).
Two
One
