Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Developmental Biology > Placenta and Extraembryonic Membranes > Flashcards

Placenta and Extraembryonic Membranes Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

amnion summary

A

ectodermal derivative; forms a protective fluid-filled capsule around the embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

allantois summary

A

endodermal derivative; associated with removal of embryonic wastes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

extraembryonic mesoderm

A

bulk of umbilical cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

amniotic fluid

A

buffer against mechanical injury; accommodates growth, allows normal fetal movements and protects the fetus from adhesions;

dilute transudate of maternal placenta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

two phases of amniotic fluid production

A

First 20 weeks of pregnancy: composition is quite similar to fetal fluids; fetal skin is unkeratinized and there is evidence that fluid and electrolytes are able to diffuse freely through embryonic ectoderm of skin; amniotic membrane secretes fluids

After first 20 weeks: increasing contributions from fetal urine, filtration from maternal blood vessels near the chorion leave; and filtration from fetal vessels in the umbilical cord and chorionic plate

fetal swallowing is important to turnover of amniotic fluid in the late pregnancy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

yolk sac

A

extraembryonic endoderm lining; formed ventral to the embryo

small and devoid of yolk; remains vital to embryo although not for nutritive purposes; may play role in prevention of neural tube defects

endoderm of yolk sac is lined on the outside by well-vascularized extraembryonic mesoderm

primordial germ cells which arise in extraembryonic mesoderm near the base of the allantois become visible in yolk sac

extraembryonic mesoderm becomes organized into blood islands and cells differentiate into primitive blood cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

extraembryonic hematopoiesis

A

occurs in yolk sac until 6th week when blood forming activity moves to the intraembryonic sites like the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Meckel’s diverticulum

A

attachment site of yolk stalk becomes less prominent, but in some adults, traces of the yolk duct persist as a fibrous cord or outpouching of small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

allantois

A

hydramnios arises from pocketing of hindgut; in humans only retains secondary function;

blood vessels that differentiate fro the mesodermal wall of the allantois; form the umbilical circulatory arc

allantois is a cord of endodermal cells and is embedded in the umbilical cord

urachus=proximal part of allantois; continuous with forming urinary bladder; after birth is transformed into dense fibrous cord (median umbilical ligament) which runs from urinary bladder to the umbilical region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

hydramnios

A

excessive amount of amniotic fluid (>2000 mL)

associated with multiple pregnancies and esophageal atresia or anencephaly (congenital anomaly characterized by gross defects of the head and often the inability to swallow)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

oligohydramnios

A

too little amniotic fluid (

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

amniocentesis

A

removing a small amount of amniotic fluid by inserting a needle through the mother’s abdomen into amniotic cavity

culture fetal cells present in amniotic fluid and examine for various chromosomal and metabolic defects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

alpha-fetoprotein

A

protein of central nervous system; high concentration in amniotic fluid is strong indicator of neural tube defects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

lecithin-to-sphingomyelin ratio

A

assess the fetal maturity by reflecting the maturity of the lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

erythroblastosis fetalis

A

Rh disease that can be assessed by examination of amniotic fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

early stages of implantation

A

original trophoblast surrounding embryo differentiates into cytotrophoblast and syncytiotrophoblast

lacunae in the rapidly expanding trophoblast have filled with maternal blood and connective tissue cells of endometrium have undergone the decidual reaction (containing increased amounts of glycogen and lipids)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

previllous embryo

A

trophoblastic tissues have no consistent gross morphological features

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

primary villi

A

cytotrophoblastic projections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

secondary villus

A

mesenchymal core within the expanding villus; surrounding the core is complete layer of cytotrophoblastic cells and outside of that is the syncytiotrophoblast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

tertiary villus

A

when blood vessels penetrate the mesenchymal core and newly formed branches (individual villi undergo considerable branching but most of them retain the same basic structural plan throughout pregnancy)

near 3rd week of pregnancy

allow embryonic blood to come close to the maternal blood without actually touching it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Msx2 and Dlx4

A

genes expressed at interface between the trophoblast and the underlying extraembryonic mesenchyme

often at sites of epitheliomesenchymal interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Gem-1

A

TF which promotes an exist from the cell cycle; expressed at branching points on the villi;

cytotrophoblastic cells on either side of the region of Gem-1 expression continue to proliferate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

cytotrophoblastic cell column

A

terminal portion of the villus remains trophoblastic, consisting of a sold mass of cytotrophoblast; covered by relatively thin layer of syncytiotrophoblast

villus is bathed in maternal blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

cytotrophoblastic shell

A

local hypoxic environment causes cytotrophoblastic cell column to expand distally and penetrate the syncytiotrophoblastic layer; abut directly on maternal decidual cells and spread over them to form complete cellular layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

anchoring villi

A

villi that give off the cytotrophoblastic extensions; they represent the real attachment points between the embryo complex and the maternal tissues

by means of cytotrophoblastic cell columns, it attaches the villus complex to the outer cytotrophoblastic shell

26
Q

overall relationships of the various embryonic and maternal tissues

A

embryo is attached to the body stalk (umbilical cord) and suspended in the chorionic cavity, which is bound to the chorionic plate (extraembryonic mesoderm overlaid with trophoblast)

chorionic villi extend outward from the chorionic plate and their trophoblastic covering is continuous with that of the chorionic plate

villi and outer surface of the chorionic plate are bathed in a sea of continually exchanging maternal blood

human placenta is hemochorial type

27
Q

floating villi

A

unattached branches dangle freely in maternal blood that fills the space between the chorionic plate and he outer cytotrophoblastic shell

28
Q

what does the syncytiotrophoblast line continuously?

A

all surfaces of he villi, chorionic plate, and cytotrophoblastic shell that are in contact with maternal blood

29
Q

uteroplacental circulation

A

serves as the medium for bringing food and oxygen to and removing wastes from the embryo

30
Q

spiral arteries

A

walls are eroded and modified so that, as the embryo grows, these arteries can provide an increasing flow of blood at low pressure to bathe the syncytiotrophoblastic surface of the placenta

31
Q

invasive cytrophoblastic cells

A

migrate out from anchoring villi; invade the spiral arteries, but not the veins; cause major modifications of their walls by secreting a specialized ECM and displacing many of the normal cellular elements of the spiral arteries; arteries become wider but blood escaping from their open end leaves at much lower pressure than normal arterial pressure

32
Q

results of hypoxia on cytotrophoblastic cells

A

stimulates mitosis; explains the rapid growth of the cytotrophoblast during the early embryonic period

after 12 weeks, switch from embryonic to fetal hemoglobin as oxygen content increases from maternal blood

33
Q

decidual reaction and decidual cells

A

stromal cells swell as the result of accumulation of glycogen and lipids in their cytoplasm

spreads through stromal cells of he superficial layers of the endometrium

34
Q

decidua capsularis

A

decidual tissue that overlies the embryo and its chorionic vesicle

35
Q

decidua basalis

A

lies between the chorionic vesicle and the uterine wall

becomes incorporated into the maternal component of the definitive placenta

36
Q

decidua parietalis

A

remaining decidua, decidualized endometrial tissue on the sides of the uterus not occupied by the embryo

37
Q

chorion

A

layer consisting of the trophoblast and the underlying exraembryonic mesoderm

forms complete covering (chorionic vesicle) that surrounds the embryo, amnion, yolk sac, and body stalk

villi at first project from the entire outer surface of the chorionic vesicle

38
Q

chorion frondosum

A

region that contains the flourishing chorionic villi and ultimately becomes placenta;

extension and growth of villi that preferentially occurs nearest to the decidua basalis

39
Q

chorion laeve

A

ultimately becomes smooth; chorion villi that are located on the opposite side (the abembryonic pole) of the chorionic vesicle that fail to keep up and eventually atrophy as the growing embryo complex bulges into the uterine cavity

oxidative stress may play a role

40
Q

fate of decidua capsularis

A

growth of chorionic vesicle pushes the decidua capsularis farther form the endometrial blood vessels; by the end of the first trimester, decidua capsularis undergoes pronounced atrophy and begins to disappear, leaving portions of the chorion leave in direct contact with decidua parietalis on the opposite side of the uterus

decidua capsularis fuses with decidua parietalis by mid-pregnancy

41
Q

fetal component of the placenta

A

part of the chorionic vesicle represented by the chorion frondosum–wall of chorion (chorionic plate) and the chorionic villi that arise from that region

42
Q

maternal component of the placenta

A

decidua basalis;; covering of decidua basalis is fetally derived outer cytotrophoblastic shell

43
Q

intervillous space of placenta

A

occupied by freely circulating maternal blood

44
Q

structure of mature placenta

A

weights about 500 g; fetal side of the placenta is shiny because of the apposed amniotic membrane

from the fetal side, attachment of umbilical cord to the chorionic plate and the large placental branches of the umbilical arteries and vein radiating from it are evident

maternal side of placenta is dull and subdivided into as many as 35 lobes; placental septa between lobes arise from decidua basalis and extend toward the basal plate

within placental lobe are several cotyledons = main stem villus and all of its branches

intervillous space of each lobe is a nearly isolated compartment of the maternal circulation to the placenta

45
Q

umbilical cord

A

conduit for the umbilical vessels which are embedded in a mucoid connective tissue called Wharton’s jelly

50-60cm at end of pregnancy; typically twisted many times;

contains 2 arteries and 1 vein; occasionally will have 2 veins if the right umbilical vein doesn’t undergo its normal degeneration

46
Q

placental circulation

A

both mother and fetus contribute to this; fetal blood reaches placenta through 2 umbilical arteries and break up into successively smaller branches which then consolidate into larger and larger venous branches ==> one vein back to fetus

maternal circulation is free-flowing lake that is not bounded by vessel walls==> 80-100 spiral arteries open directly into intervillous space releasing about 150 mL of maternal blood

maternal blood enters at reduced pressure due to cytotrophoblastic plugs

placental barrier of mature placenta consists of the syncytiotrophoblast, basal lamina of the fetal capillaries; and capillary endothelium

47
Q

structure of mature chorionic villus

Hofbauer cells

A

mass of interwoven branches; core of villus is blood vessels and mesenchyme that is similar in composition of the mesenchyme of the umbilical cord

Hofbauer cells: function as fetal macrophages and are scattered among the mesenchymal cells

villus core is covered by continuous syncytiotrophoblast, surface of which is covered by microvilli, increasing the total surface area of placenta;; size and density of microvilli are not constant

trophoblastic surface contains areas that: contain numerous transport systems for substances ranging from ions to macromolecules, hormone and growth factor receptors, enzymes, numerous other proteins

placental surface is deficient and lacking major histocompatibility antigens, the absence of which plays a role in protecting against maternal immune rejection of fetus and fetal membranes

48
Q

epithelial plates

A

scattered areas where the barrier between fetal and maternal blood is extremely thin; designed to facilitate diffusion of substances between the fetal and maternal circulations

transfer goes both ways: mother gives oxygen and nutrients, baby gives carbon dioxide and fetal waste materials

49
Q

substances that readily cross placental barrier

A

gases (oxygen from mother; carbon dioxide from fetus) cross by diffusion; amount exchange limited by blood flow; carbon monoxide and inhalational anesthetics

water and electrolytes are readily transferred across placenta

fetal wastes (urea, creatinine, bilirubin) rapidly transferred across placenta

highly permeable to glucose, amino acids, some free fatty acids, water-soluble vitamins

steroid hormones cross barrier from maternal side (protein hormones in general are not transported)

some proteins transferred slowly mostly by pinocytosis

maternal antibodies (IgG)–increases throughout pregnancy beginning at 12 weeks

transferrin (maternal protein that transfers iron to the fetus)

50
Q

erythroblastosis fetalis

A

small quantities of fetal blood cells escape into maternal circulation; if you have Rh+ fetus but Rh- mother, the mother will develop antibodies to Rh+ cells; first child is okay but subsequent pregnancies are attacked by maternal anti-Rh antibodies which make their way into fetal bloodstream

antibody causes hemolysis of Rh-+ fetal erythrocytes

51
Q

human chorionic gonadotropin (HCG)

A

first protein hormone produced by placenta (syncytiotrophoblast);

responsible for maintaining corpus luteum and its production of progesterone and estrogen

synthesis begins even before implantation

production peaks at ~8 weeks and then gradually declines

52
Q

progesterone and estrogen

A

produced by the placenta; pregnancy can be maintained even if corpus luteum is removed;

progesterone from acetate or cholesterol precursors but doesn’t contain machinery needed to make estrogens; placenta must operate in concert with fetal adrenal gland and possibly the liver to make estrogens

53
Q

chorionic somatomammotropin

A

human placental lactogen

similar to HGH, influences growth, lactation, lipid and carbohydrate metabolism

placenta also produces chorionic thyrotropin and chorionic corticotropin

54
Q

human placental growth hormone

A

produced by syncytiotrophoblast; influences growth of placenta by paracrine fashion

exerts profound effect on mother; replaces maternal pituitary growth hormone;

regulation of maternal blood glucose levels so that the fetus is ensured of an adequate nutrient supply

55
Q

placental immunology

A

thought that fetal tissues like placenta that interface with mother do not present foreign antigens to the mother’s immune system –somewhat true because syncytiotrophoblast and cytotrophoblastic shell do not present antigens but they are found on cells of fetus and in stromal tissues of the placenta

fetal RBCs and WBCs found circulating in the maternal blood

possible that mothers immune system is paralyzed during pregnancy but mother is capable of mounting immune response to other invaders

possible that local decidual barriers prevent either immune recognition of the fetus by the mother or the reaching of competent immune cells from the mother to the fetus

molecules formed on the fetal placental surface might be able to inactivate the T cells or other immune cells locally

56
Q

placenta previa

A

abnormal implantation sites with the uterine cavity;; part of placenta may cover the cervical outlet of the uterine cavity, mechanical obstacle in the birth canal; may also result in fatal hemorrhage

57
Q

velamentous insertion

A

if umbilical cod attaches to the smooth membranes outside the boundaries of the placenta itself

58
Q

accessory lobes

A

placenta can be subdivided into accessory lobes or completely divided into two parts

59
Q

hydatidiform mole

A

noninvasive condition in which many of the chorionic villi are characterized by nodular swellings that give them an appearance similar to a bunch of grapes; embryo is either absent or not viable ; villi show no signs of vascularization

result of paternal imprinting in which female pronucleus of the egg does not participate in development

60
Q

choriocarninomas

A

malignant tumors derived from embryonic cytotrophoblast and syncytiotrophoblast ; contain only paternally derived chromosomes and products of paternal imprinting

61
Q

twin-to-twin transfusion syndrome

A

when vascular systems are fused, one twin may receive a greater proportion of the placental blood flow; may result in mild to severe stunting of growth of the embryo that receives the lesser amount of blood; twin with less blood is misshapen and called acardiac monster

Developmental Biology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions