Embryo-6-Placenta and Amniotic Fluid

How is amniotic fluid resorbed during pregnancy?

-Fetal swallows amniotic fluid -Amniotic fluid is absorbed into the fetal blood stream through the gastrointestinal tract. -Excess amniotic fluid is removed via the placenta into the maternal blood stream

The Placental membrane consists of four layers, what are they?

-Syncytiotrophoblast -Cytotrophoblast -Connective tissue of villus -Endothelium of fetal capillaries

Oligohydramnios (____ ml in late pregnancy). Polyhydramnios (____ ml in late pregnancy)

400, 2000

Median umbilical ligament is the remnants of _______

Allantois

What is transferin? What does it do?

Its a maternal protein that crosses the placental membrane and carries IRON to the embryo/fetus

_________ is the remnants of Allantois

Median umbilical ligament

What is the role of the placenta and Umbilical cord?

The placenta and umbilical cord function as a transport system for substances passing between the mother and fetus.

Explain the formation of the placenta...

The placenta is formed as the endometrium of the uterus is invaded by the developing embryo and as the TROPHOBLAST forms the VILLOUS CHORION

Testosterone and progestins can cross the placental membrane, therefore, does this affect the female fetuses, how?

Yes, it may cause masculinization of female fetuses.

T/F Polyhydramnios may also be related to decreased fluid production, as is the case with certain fetal lung disorders.

false, INCREASED fluid production

Nutrients and oxygen pass from the _____ blood through the _______ to the ______ blood

maternal, placenta, fetal

What congenital malformation in which there is premature separation of a placenta from its implantation in the uterus.

placental abruption

The circulations of the fetus and the mother are separated by the ________ which consists of ________

placental membrane, extrafetal tissues

One of the hormones produced/synthesized by the Placenta is Prolactin. What is the significance of this hormone?

prepares mammary glands for breast feeding

One of the hormones produced/synthesized by the Placenta is Relaxin. What is the significance of this hormone?

relaxes the pelvic cavity to make space for the pregnancy & it helps for dilation and relaxing the joints of pelvic cavity during delivery

What are the symptoms of Choriocarcinoma?

repeated uterine bleeding

The villous chorion is in contrast to an area of no villus development known as the ________ ( which is related to the ________).

smooth chorion, decidua capsularis

How does Choriocarcinoma metastasize?

through the blood stream

T/F Protein hormones reach the embryo or fetus in significant amounts

false, Protein hormones do not reach the embryo or fetus in significant amounts.

T/F fat-soluble vitamins cross the placental membrane more quickly than water-soluble vitamins

false, Water-soluble vitamins cross the placental membrane more quickly than fat-soluble ones.

T/F Complete hydatiform mole is associated with HIGH hCG levels and Choriocarcinoma is associated with LOW hCG levels

false, both are associated with high hCG levels because they are both associated with proliferation of trophoblast which secretes hCG

T/F Most drugs and drug metabolites cross the placenta by facilitated diffusion

false, simple diffusion

T/F Poorly oxygenated blood leaves the fetus and passes through the umbilical veins to the placenta.

false, umbilical arteries

Waste materials and Carbon dioxide pass from the _______ blood through the ________ to the _______ blood

fetal, placenta, maternal

The placenta synthesizes ____________ which serve as sources of nutrients and energy for the embryo/fetus

glycogen, cholesterol, and fatty acids

One of the hormones produced/synthesized by the Placenta is a small amount of estrogen. What is the significance of this hormone?

helps for thickness of the endometrium (like pillow for the fetus for sleeping)

One of the hormones produced/synthesized by the Placenta is a very small amount of testosterone. What is the significance of this hormone?

important for descending of testis from abdominal cavity into the scrotum in the male fetus during intrauterine life

One of the hormones produced/synthesized by the Placenta is Prostaglandins. What is the significance of this hormone?

important for relaxation, dilation of cervix during delivery

The amount of amniotic fluid is gradually ________ during pregnancy from ___ ml at week __ of development to ___ ml at term.

increased, 50, 12, 1000

What is Choriocarcinoma?

is a malignant tumor of the TROPHOBLAST which presents clinically as repeated uterine bleeding.

One of the hormones produced/synthesized by the Placenta is human chorionic gonadotrophin (hCG). What is the significance of this hormone?

its important for pregnancy, a postive sign for pregnancy in blood or urine, maintains the corpus luteum to produce progesterone which is very important for pregnancy

One of the hormones produced/synthesized by the Placenta is human chorionic adrenocorticotropin (hACT). What is the significance of this hormone?

its the precursor for ACTh, stimulates the secretion of 3 hormones from the Adrenal Cortex: cortisol, aldosterone, and androgen (male sex hormone)

One of the hormones produced/synthesized by the Placenta is human placental lactogen (hPL). What is the significance of this hormone?

its the precursor for growth hormone, which controls cell division, cell growth, number of cells, and the size of cells

One of the hormones produced/synthesized by the Placenta is human chorionic thyrotropin (hCT). What is the significance of this hormone?

its the precursor for thyroid hormone. controls the thyroid gland development in fetus and controls the CNS development and bone development of fetus during intrauterine life.

What are some of the things that can happen to the baby if the mother has hypothyroidism?

mental retardation, bone development retardation, speech disorder, learning disorder, and behavior disorder

What is amniotic band syndrome? what type of abnormalities does it lead to in the fetus?

occurs when bands of amniotic membrane encircle and constrict various parts of the fetus, causing limb and craniofacial anomalies.

T/F Electrolytes are FREELY exchanged across the placental membrane in significant quantities, each at its own rate

true

T/F The decidua parietalis includes all portions of the endometrium other than the site of implantation

true

T/F arterial pressure is always higher than venous pressure

true

T/F the four main transport mechanisms for Placental Transfer are important because one of their main functions is to allow excretion of waste products by the fetus.

true

One of the hormones produced/synthesized by the Placenta is Progesterone. What is the significance of this hormone?

very important for pregnancy. keep in mind that the placenta only produces progesterone AFTER the first 3 months, before that, the corpus luteum is what produces the progesterone which is under regulation of hCG secreted by the placenta

The placenta is formed as the endometrium of the uterus is invaded by the developing embryo and as the TROPHOBLAST forms the __________.

villous chorion

Can HIV cross the placenta?

yes, because its a virus

Does Interruption of oxygen transport for several minutes endangers survival of the embryo or fetus?

yes, fetus/embryo ALWAYS needs oxygen for survival

The placenta is a feto-maternal organ that has 2 components, what are they? What is each derived from?

-A fetal portion that develops from the chorionic sac. -A maternal portion that is derived from the endometrium.

What/Where is the umbilical ring? What structures pass through the primitive umbilical ring?

-A patent opening called the primitive umbilical ring exists on the ventral surface the developing embryo - Three structures pass through the primitive umbilical ring: yolk sac (vital-line duct, connecting stalk, allantois.

Explain how the yolk sac and allantois degenerate?

-At week 6 of development, the gut tube connected to the yolk sac will herniate (physiological umbilical herniation) into the extraembryonic coelom; the herniation will be reduced by week 11. -The gut tube eventually returns to the abdominal cavity; the yolk sac (vitelline duct) and allantois degenerate.

What are the signs and symptoms of Polyhydraminos?

-Mild hydramnios often has no symptoms. -Breathlessness -Abdominal pain -Swelling or bloating which can be signs of more severe hydramnios.

What substances cross the placenta from the mother to the baby?

-Oxygen -Water and Electrolytes -Nutrients -Hormones -Antibodies -Drugs -Viruses

When the Villous chorion forms from the trophoblast, it goes through three layers. What are these 3 layers?

-Primary chorionic villi -Secondary chorionic villi -Tertiary chorionic villi

What are all the functions and activities performed by the placenta and membranes?

-Protection for the fetus through anti-bodies/immune cells, (IgG crosses placenta) -Nutrition (provides nutrients, proteins etc to the baby) -Respiration (facilitates cell respiration, gas exchange) -Excretion (wastes, CO2 are excreted by umbilical arteries from fetus to mom) -Hormone production

What are the main transport mechanisms for Placental Transfer? Explain how each of them works

-Simple diffusion: is usually characteristic of substances moving from areas of higher to lower concentration until equilibrium is established. -Facilitated diffusion: There is transport through electrical charges. -Active transport: Against a concentration gradient requires energy. -Pinocytosis: is a form of endocytosis in which the material being engulfed is a small sample of extracellular fluid.

What Maternal Antibodies are transported across the placental membrane? what is their method of transport

-The alpha and beta globulins reach the fetus in very SMALL quantities -many gamma globulins, such as the IgG class are readily transported to the fetus by PINOCYTOSIS.

How much urine does the near term fetus excrete daily? What is it mostly composed of? How much amniotic fluid does the fetus swallow daily?

-The near-term fetus excretes about 500 ml of urine daily -is mostly water because the placenta exchanges metabolic wastes. -The fetus swallows about 400 ml of amniotic fluid daily.

What are the abnormal shapes of the placenta

-Velamentous placenta -Bipartite or tripartite placenta -Duplex or triplex placenta -Succenturiate placenta -Membranous placenta -Bilobate placenta

What NUTRITIONAL SUBSTANCES are passed through the placenta and what is their method of transport?

-Water is rapidly and freely exchanged by SIMPLE DIFFUSION between the mother and fetus. -Glucose produced by the mother and placenta is quickly transferred to the embryo or fetus by DIFFUSION. -Vitamins also cross the placental membrane and are essential for normal development.

How many umbilical veins are there in the umbilical cord connecting to the fetus? How many umbilical arteries? What does each carry?

-We have ONE umbilical vein, which carries OXYGENATED blood, nutrients, gasses, antibodies, vitamins, hormones etc from MOTHER to FETUS -We have TWO umbilical arteries which carry the DE-OXYGENATED blood from FETUS to MOTHER (maternal blood vessels)

Why does the fetus only produce a small amount of antibodies? How does it overcome this bad immune system?

-because its immune system is still very immature -many gamma globulins, such as the IgG class are readily transported to the fetus by pinocytosis.

What substances cross the placenta from the baby to the mother?

-carbon dioxide -water and urea -waste products -hormones

What hormones are synthesized/produced by the Placenta?

-human chorionic gonadotropin (hCG) -human placental lactogen (hPL) -human chorionic thyrotropin (hCT) -human chorionic adrenocorticotropin (hACT) -prolactin -relaxin -prostaglandins -progesterone -very small amnt of testosterone -small amount of estrogen -cytokines/growth factors

What is Oligohydraminos? What congenital abnormality mentioned in class was it associated with and why?

-is a condition in pregnancy characterized by a DEFICIENCY of amniotic fluid. -its associated with unilateral or bilateral renal agenesis in which the kidney cannot develop, so it cannot filtrate any fluid so leads to less fluid. other causes include posterior urethral valves, and bilateral multicystic dysplastic kidneys.

What is Polyhydraminos? What congenital abnormality mentioned in class was it associated with and why?

-is a condition in pregnancy characterized by a EXCESS of amniotic fluid. -is associated with ESOPHAGEAL ATRESIA in which the fetus cannot swallow the fluid so leads to excess fluid. This may occur as a result of gastrointestinal disorders, neurological problems, or a variety of other causes.

What is the appearance of the MATERNAL surface of the placenta in afterbirth?

-is characterized by 15 to 20 compartments called cotyledons, which are seperated by decidual (placental) septa. -is dark red in color.

What is the appearance of the FETAL surface of the placenta in afterbirth?

-is characterized by the well-vascularized chorionic plate containing the chorionic blood vessels. -It has a smooth and shiny appearance because of the amnion

What is the decidua capsularis? When does it shed off and why?

-its the superficial part of the decidua overlying the conceptus. the portion of endometrium that covers the blastocyst and separates it from the uterine cavity -becomes attenuated and degenerates at week 22 of development because of a reduced blood supply

what does the fetal component of the placenta consist of?

-mainly of the Chorionic Villi, consists of tertiary chorionic villi derived from both the trophoblast and extraembryonic mesoderm, which collectively become known as the VILLOUS CHORION.

Describe the 3 layers of the decidua...

-the DECIDUA BASALIS: is the part of the decidua deep to the conceptus that forms the MATERNAL component of the placenta. -the DECIDUA CAPSULARIS: is the superficial part of the decidua overlying the conceptus -the DECIDUA PARIETALIS (decidua vera): is all the remaining parts of the decidua

The rate of water exchange within the amniotic sac at term is ______ ml/hr, with a net flow of _______ ml/hr moving from the amniotic fluid into the maternal blood stream.

400-500, 125-200

Which dedicual layer is shed as part of the Afterbirth? A. decidua basalis B. decidua parietalis C. decidua capsularis

A,B

Choriocarcinoma may occur following ________. A. normal pregnancy B. hydatiform mole C. Amniotic band syndrome D. Erythroblastosis fetalis E. abortion

A,B,E

What are the diagnotstic aids in complete hydatiform mole, in other words, what are the signs that a complete hydatiform mole is present?

Can be detected with ultrasound, rise of hCG levels, and development of preeclamsia (which is a combination of hypertension and proteinuria)

What are some infectious agents that may cross the placental membrane cause fetal infection?

Cytomegalovirus, rubella, and viruses associated with varicella, measles, and polimyelitis

A 42-year-old woman presents with complaints of severe headaches, blurred vision, slurred speech, and loss of muscle coordination. Her last pregnancy 5 years ago resulted in a hydatidiform mole. Laboratory results show a high hCG level. Which of the following conditions is a probable diagnosis? A. Vasa previa B. Placenta previa C. Succenturiate placenta D. Choriocarcinoma E. Membranous placenta

D. After a hydatidiform mole, it is very important to ensure that all the invasive trophoblastic tissue is removed. High levels of hCG are a good indicator of retained trophoblastic tissue because such tissue produces this hormone. In this case, the trophoblastic tissue has developed into a malignant choriocarcinoma and metastasized to the brain, causing her symptoms of headache, blurred vision, and so on.

What is it called when bands of amniotic membrane encircle and constrict various parts of the fetus, causing limb and craniofacial anomalies.

Amniotic band syndrome

What are the components of the Amniotic fluid?

Amniotic fluid is basically water (99%) that contains carbohydrates, lipids, proteins (hormones, enzymes, alpha-fetoprotein), desquamated fetal cells, and fetal urine.

What is the Amniotic fluid produed by during pregnancy?

Amniotic fluid is constantly produced during pregnancy by the following: -Dialysis of maternal blood through blood vessels in the placenta -Dialysis of fetal blood through blood vessels in the placenta and umbilical cord -Excretion of fetal urine into the amniotic sac

What is Erythroblastosis fetalis?

Antibodies from an Rh negative mother may enter the blood stream of her unborn Rh positive infant, damaging the red blood cells (RBCs).

What is a complete hydatiform mole?

Its a blastocyst which is dead. Basically, the trophoblast proliferates but the embryoblast fails to proliferate and is retained in the uterine wall, followed by hyperplastic proliferation of the trophoblast and CYSTIC swelling (like bunches of grapes) fills the uterine cavity

What is the decidua?

Its the FUNCTIONAL LAYER of the endometrium in a pregnant woman

What does karyotyping show is in the case of a hydatiform mole?

Karyotyping has indicated that complete moles consist of chromosomes derived entirely from the father.

What is the primary site of NUTRIENT and GAS exchange between the Mother and Fetus?

Placenta

What is placenta previa?

Placenta previa is a condition in which the placenta is attached close to or covering the cervix (opening of the uterus).

What is placental abruption?

Placental abruption is the premature separation of a placenta from its implantation in the uterus.

What is the etiology of Polyhydraminos?

Polyhydramnios may result from failure of the fetus to swallow and absorb amniotic fluid in normal amounts. This may occur as a result of gastrointestinal disorders (esophageal atresia is a big one), neurological problems, or a variety of other causes.

One of the hormones produced/synthesized by the Placenta are cytokines/growth factors. What is the significance of this hormone?

cell proliferation, cell division, and cell growth

What does the term decidua mean?

"falling off" "shed", or sloughed off.

What are the 3 main functions of the placenta?

1. Metabolism 2. Transport 3. Endocrine secretion

Explain how the primitive umbilical cord forms?

As the amnion expands, it pushes the vitelline duct, connecting stalk, and allantois together to form the primitive umblical cord

What is physiological umbilical herniation and when does it happen?

At week 6 of development, the gut tube connected to the yolk sac will herniate (physiological umbilical herniation) into the extraembryonic coelom; the herniation will be reduced by week 11.

Which of the following is NOT contained in the definitive umbilical cord? A. right and left umbilical arteries B. right and left umbilical veins C. amniotic fluid D. Wharton's jelly

B,C. -only the left umbilical VEIN is there, not the right

Maternal antibodies (IgG) can confer fetal immunity to all of the following except: A. diphtheria B. varicella C. meals D. smallpox E. chickenpox

B,E -varicella IS chickenpox

How does the infant respond to Erythroblastosis fetalis?

The infant responds by increasing RBC production and sending out immature RBCs that still have nuclei.

What are the signs and symptoms of Oligohydramnios?

Nonrenal etiologies include intrauterine growth retardation, post-term pregnancy, fetal demise, and ruptured membranes. Due to the lack of amniotic fluid, the lungs are hypoplastic (underdeveloped) and neonates who survive delivery die of respiratory failure.

What GASSES pass through the placenta and what is their method of transport?

O2 carbon dioxide, and carbon monoxide cross the placental membrane by simple diffusion.

What is the most common cause of oligohydraminos?

Permature rupture of the amniochorionic membrane

What is the most common cause of premature labor?

Permature rupture of the amniochorionic membrane

Which pathological condition is commonly referred to as "breaking of the waters"?

Permature rupture of the amniochorionic membrane

In the fetal placental circulation, explain what happens to the poorly oxygenated blood that leaves the fetus...

Poorly oxygenated blood leaves the fetus and passes through the UMBILICAL ARTERIES to the placenta. At the site of attachment of the cord to the placenta, these arteries divide into number of CHORIONIC ARTERIES that branch freely in the CHORIONIC PLATE before entering the CHORIONIC VILLI. These blood vessels form an extensive arterio-capillary-venous system within the chorionic villi, which brings the fetal blood extremely close to the maternal blood so that exchange of metabolic and gaseous products between the maternal and fetal blood streams can occur

What happens when there is presence of only one umbilical artery within the umbilical cord?

Presence of one umbilical artery within the cord is an abnormal condition that generally indicates the presence of cardiovascular anomalies. (Normally two umbilical arteries are present).

What are the Etiology/causes of Oligohydraminos?

Profound oligohydramnios may result from fetal urinary tract anomalies that include bilateral renal agenesis, posterior urethral valves, and bilateral multicystic dysplastic kidneys.

What is the function of the allantois in the humans? What does it form when it degenerates?

The allantois is not functional in humans and degenerates to form the median umbilical ligament in the adult.

In the fetal placental circulation, explain how the well-oxygenated blood gets to the fetus.....

The well-oxygenated fetal blood in the fetal capillaries gets there by passing into thin-walled VEINS that follow the CHORIONIC ARTERIES to the site of attachment of the umbilical cord, here they converge to form the UMBILICAL VEIN. This large vessel carries oxygen-rich blood to the fetus.

In the Maternal placenta circulation, explain how the exchange of metabolic and gaseous products occurs with the fetal blood...

There is a space called the INTERVILLOUS SPACE between the maternal and fetal circulation systems. The blood in the intervillous space is temporarily outside the maternal circulatory system. It enters the intervillous space through 80 to 100 SPIRAL ENDOMETRIAL ARTERIES in the DECIDUA BASALIS. These vessels discharge into the intervillous space through gaps in the CYTOTROPHOBLASTIC SHELL. The blood flow from the spiral arteries is pulsatile and is propelled in jetlike fountains by the maternal blood pressure. The entering blood is at a considerably higher pressure than that in the intervillous space. As the pressure dissipates, the blood flows slowly around the branch villi, allowing an exchange of metabolic and gaseous products with the fetal blood.

It is through the numerous ______ villi, which arise from the ______ villi, that the main exchange of material between the mother and fetus takes place.

branch, stem

Which of the following hormones cross the placental membrane to the fetus? A. Protein hormones B. Unconjugated steroid hormones C. Testosterone D. Progesterone

all of the above, but Protein hormones do not reach the embryo or fetus in significant amounts.

The decidua _______ forms the MATERNAL component of the placenta, which is derived from the endometrium of the uterus located between the BLASTOCYST and the MYOMETRIUM

basalis

The villous chorion develops most prolifically at the site of the decidua _______.

basalis