37- Placental & Fetal Membranes Flashcards
What are the fetal membranes?
Chorion
Amnion
Umbilical Vesicle
Allantois
Placenta is a fetomaternal organ with two components, which are…
Fetal Part = chorionic sac (outermost fetal membrane)
Maternal Part = derived from endometrium
Exchanges of nutrients and oxygen occurs between maternal and fetal bloodstreams via the ________.
Placenta
Vessels in the _______ _______ connect the placental circulation with the fetal circulation.
Umbilical Cord
What type of potency is a zygote?
Totipotent
***Can give rise to any cell type!
Expression of cell lineage specific factors begins in the blastocyst. The _________ will become the embryo and the _________ will become the extraembryonic tissue.
Embryoblast
Trophoblast
Implantation occurs and embryoblast becomes a…
Bilaminar embryonic disc
What do the extraembryonic structures include?
Amnion
Umbilical Vesicle
Connecting Stalk
Chorionic Sac
This is the functional layer of the endometrium that separates from the remainder of the uterus after parturition (childbirth).
Decidua
***Pale-staining cells with glycogen and lipid accumulation!
This part of the decidua is deep to the conceptus and forms the maternal part of the placenta.
Decidua Basalis
This part of the decidua is superficial and overlies the conceptus.
Decidua Capsularis
This part of the decidua consists of all its remaining parts.
Decidua Parietalis
Cellular and vascular changes occur to the endometrium as the blastocyst implants. This is called the…
Decidual Reaction (Decidualization)
This is completed the late 2nd week (about 10 days post-fertilization) and is when the blastocyst embeds in the endometrium.
Implantation
In implantation, the trophoblast differentiates into what?
Cytotrophoblast (inner layer)
Syncytiotrophoblast (outer layer) – invades and displaces decidual cells of the endometrium
_________ appear in syncytiotrophoblast layer and fill with blood and uterine secretions. Adjacent ones fuse to form networks.
Lacunae
_______ _______ _______ is when oxygen and nutritive substances pass to the embryo via diffusion through lacunar networks.
Primordial Uteroplacental Circulation
Put the following steps of implantation in order –
A. Blood-filled lacunae appear in the syncytiotrophoblast.
B. Primary chorionic villi develop.
C. Implantation of the blastocyst in the uterine endometrium begins at the end of 1st week, completed by end of 2nd week.
D. Lacunar networks form by fusion of adjacent lacunae.
E. Blastocyst adheres to the endometrial epithelium.
F. ZP degenerates due to enlarging the blastocyst and enzymatic lysis.
G. Syncytiotrophoblast erodes endometrial blood vessels, allowing maternal blood to seep in and out of lacunar networks, and establishing uteroplacental circulation.
H. Trophoblast differentiates into two layers, the syncytiotrophoblast and cytotrophoblast.
1) C.
2) F.
3) E.
4) H.
5) A.
6) D.
7) G.
8) B.
***Look at slides for exact days!
This is the implantation of blastocyst outside the uterine cavity (2% of all pregnancies). Most occur in the oviduct, most frequently in the ampulla and isthmus. Signs can include abdominal pain, amenorrhea, vaginal bleeding, rupture of oviduct wall, and surgical removal of affected tubes/conceptus.
Ectopic Pregnancy
T/F. Ectopic pregnancies produce a highly increased amount of hCG than a regular pregnancy.
False. Ectopic pregnancies produce hCG but at a slower rate than normal pregnancies.
This type of mesoderm lines the trophoblast and covers the amnion.
Extraembryonic Somatic Mesoderm
This type of mesoderm surrounds the umbilical vesicle.
Extraembryonic Splanchnic Mesoderm
This is a fluid-filled cavity that surrounds the amnion and umbilical vesicle.
Extraembryonic Coelom
What do the following collectively make?
- Extraembryonic Somatic Mesoderm
- Cytotrophoblasts
- Syncytiotrophoblasts
Chorionic Sac
This is a thin, tough membrane that surrounds the embryo/fetus and amniotic fluid.
Amnion (Amniotic Sac)
________ separate from the epiblast and enclose the developing amniotic cavity.
Amnioblasts
Amnion will eventually obliterate chorionic cavity and form epithelial covering of the…
Umbilical Cord
This cushions the fetus, permits fetal movements, and regulates fetal body temperature. It’s composed of organic compounds (proteins, carbs, fats, enzymes, hormones) and inorganic salts, ions, glycophospholipids, and steroid hormones.
Amniotic Fluid
Amniotic fluid is initially derived from maternal tissue and interstitial fluid. The _______ _______ ______ will excrete amniotic fluid (500 mL/day) at 11 weeks, as well as the ________ ________ and ________ ________ (300-400 mL). It is a dialysis-like exchange via the umbilical cord.
Fetal Urinary System
Respiratory System
GI Tract
This is the term for excessive amniotic fluid. It is due to a genetic defect, a fetal defect in the CNS, or blockage of the GI tube. Clinical signs include abdominal pain, significant swelling or bloating, and breathlessness.
Hydramnios
This is the term for insufficient amniotic fluid (< 400 mL). Problem with fetal development (renal agenesis, pulmonary hypoplasia). There is placental abnormality or maternal HBP. Decreased fluid does not create enough cushion to fetus and umbilical cord.
Oligohydramnios
***Remember, a normal amount of amniotic fluid at 37 weeks is 700-1000 mL!
The ________ ________ forms a capsule covering the surface of the chorionic sac.
Decidua Capsularis