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132 Cards in this Set

  • Front
  • Back
what's the definition of implantation?
is blastocyst attachment to endometrium and development of a stable connection to the uterus
what does successful implantation require of development of blastocyst and preparation of endometrium?
needs to be synchronized
what is the placenta?
is an organ formed from blastocyst-derived tissues attached to uterus
what structure carries the maternal circulating blood?
what does placenta do?
mediates exchange of nutrients and metabolic waste products tween cardiovascular system of mom and fetus
when does the placenta begin to develop?
as soon as blastocyst attaches to endometrium
what's the definition of a blastocyst?
early embryo - usually there by 5 days of gestation
is hollow, spherical structure with inner cell mass surrounded by cytotrophoblast cells
whole thing surrounded by zona pellucida PRIOR to attaching to uterus
what's a trophoblast?
is outer layer of blastocyst
initially composed of cytotrophoblast cells
these fuse to form syncytial trophoblast
cytotrophoblast and syncytial trophoblast incrase in number and contribute to formation of placenta
what are cytotrophoblast cells?
are mitoticallly active mononucleated cells that forms inital trophoblast
what is the syncytial trophoblast?
is a fusion of cytotrophoblast cells
is large, multinucleated mass which is mitotically inactive
what's the chorion?
is trophoblast and adjacent extraembryonic fetal mesoderm
what's the decidua?
is just endometrium of pregnancy
what are decidual cells?
are enlarged endometrial stromal cells or fibroblasts that are the result of hormonal stimulation
what does the decidua do?
helps establish placneta
limits trophoblast invasion
decidual cells produce hormones, cell adhesion molecules, growth factors
can be divided into decidua basalis, decidua capsularis, and decidua parietalis
what do decidual cells do?
produce hormones, cell adhesion molecules, growth factors
what is the decidua basalis?
is part of decidua attached to the placenta
what is the decidua capsularis?
is part of placenta adjacent to embryo but on side toward uterine lumen
what is the decidua parietalis?
is decidua minus decidua basalis and decidua capsularis
when does the morula enter the uterus?
usually by 4th day following fertilization
what is a morula?
just mass of cells from cleavage of ovum before official formation of blastocyst
how is a blastocyst formed from a morula?
according to syllabus, requires appearance of spaces between cells of morula
where's the syncytial trophoblast when the blastocyst is lying free in uterus?
is adjacent to inner cell mass
what happens to zona pellucida while blastocyst is still lying free in uterus?
it's shed
what happens to the blastocyst on day 8 following ovulation?
it attaches to endometrial surface
how big is the blastocyst when it attaches to the endometrium, how many cells does it contain?
is about 0.1 mm in diameter with 125-250 cells
when does blastocyst typically attach to endometrium?
day 8 after ovulation
what's syncytial trophoblast doing 9 days after ovulation?
is eating through uterine epithelium
forms deep microvillous-lined invaginations called clefts and then lacunae when they get bigger
what does syncytial trophoblast do typically 10 days after ovulation?
achieves first contact with maternal blood by invading endometrial sinusoids
this allows maternal blood to enter lacunae
what is the lacunar stage of development in embryology?
happens about 10 days after ovulation when syncytial trophoblast establishes first communication with maternal blood, allowing maternal blood to fill invagination of uterine epithelium that it dug out at day 8
what are the endometrial sinusoids?
are just dilated capillaries
what are lacunae initially called?
at the end of lacunar stage of development, what's happening with cytotrophoblast cells and syncytial trophoblast?
cytotrophoblast cells - forming inner layer of placenta
syncytial trophoblast forms outermost placental layer
what are primary villi?
are incomplete partitions through lacunae, NOT blastocyst, of cytotrophoblast cell columns covered by syncytial trophoblast
are OUTGROWTHS of cytotrophoblast cells reaching out to uterine lining from inside blastocyst?
when do the primary villi appear?
12 days after ovulation
what significant event happens 12 days after ovulation?
primary villi form
what is the trophoblastic shell?
are interconnections of lateral growth of primary villi where cytotrophoblast columns pushed through syncytium, and has contact with endometrial stroma,
how are primary villi converted to secondary villi?
extraembryonic mesoderm extends into centers of interconnected primary villi
when are secondary villi formed?
about 14 days after ovulation
what happens about 14 days after ovulation?
secondary villi are formed
what are tertiary villi?
are embryonic blood vessels in extraembryonic mesoderm
where do tertiary villi form?
18 days after ovulation
what happens 18 days after ovulation?
tertiary villi form
when does the fetal heart begin to beat and move blood through the placenta?
21 days after ovulation
what happens 21 days after ovulation?
fetal heart begins to beat and move blood through placenta
where are placental villi initially found?
around entire conceptus
what happens to most of early placental villi?
deteriorate and disappear due to growth of embryo which compresses adjacent maternal vessels as well
what is the chorion laeve?
is AREA of deteriorated villi from expansion of embryo and compression of maternal blood supply to embryo
what does chorion laeve mean?
nonvillous or smooth chorion
when does chorion laeve form?
around 8 weeks of gestation
what structures can be seen pertaining to chorion at about 8 weeks of gestation?
chorion laeve forms in certain areas
what's the chorion frondosum?
is definitive placenta
consists of villi left over after some disappear from growth of embryo (chorion laeve)
villi associated with main portion of decidua basalis and therefore has good blood supply
what is the intervillous space?
are expansions of lacunae, or maternal blood vessels
where does intervillus space get its blood from?
spiral arteries that are connected to intervillous space via cytotrophoblast-established connection
how are direct connections made between maternal arteries, veins and placental intervillous space?
from continued invastion of endometrium by trophoblast cells
what are infra-arterial cytotrophoblast cells?
are cohesive groups of cytotrophoblast cells that migrate along arterial endothelium AGAINST blood flow
what do infra-arterial cytotrophoblast cells do?
are very important for development of embryo - connect maternal blood supply to developing placenta
reorganize large portions of arteries by invading walls
how is blood in the intervillous space returned to maternal circulation?
endometrial veins
what is the villous trophoblast?
is epithelium of villi
where is the extravillous trophoblast?
is on chorionic plate, trophoblastic shell, in maternal blood vessels, migrate within uterine wall
what is the shape and size of fully developed placenta - how much does it weigh, how thick is it at center, what is its diameter?
shape: circular or oval disc
diameter: 22 cm
thickness: 2.5 cm
weight: 500 g
which side of the placenta is the umbilical cord on?
fetal or amniotic side
which side of the delivered placenta has blood clots, small amounts of endometrial tissue attached?
maternal side of course
what are the two different sides of the placenta they're recognizing?
fetal/amniotic side and maternal side
what are on the maternal side of the placenta when its delivered?
blood clots, small amounts of endometrial tissue
what's the volume of maternal blood in the placenta at delivery?
150 ml
at what rate is maternal blood delivered to the placenta and through which arteries?
600 ml/min through
80-100 spiral arteries
what's another name for the fetal side of the placenta?
what's the chorionic plate?
is roof or fetal side of the placenta
what makes up the chorionic plate? this about 5 layers of things to discuss
1. layer of syncytial trophoblast in contact with maternal blood
2. above is supported by cytotrophoblast cells resting on basal lamina
3. layer of fetal connective tissue under what i've described above
4. large branches of umbilical arteries and tributaries of umbilical vein are on ct surface, entering villi
5. large stem villi come out from chorionic plate, branch, then attach to trophoblastic shell or floor of placenta
6. no cytotrophoblastic cell columns
what are stem villi?
are villi before anchoring villi - same structure, different name
villi that emanate from chorionic plate and branch
have large branches of umbilical vessels that divide with stem villi
what's another name for the trophoblastic shell of the placenta?
what's the floor of the placenta referring to?
trophoblastic shell
what are anchoring villi?
are stem villi that are attached to trophoblastic shell or floor of placenta
what do anchoring villi do in early gestation?
are attached to placental floor by cytotrophoblastic cell columns
what do cytotrophoblastic cell columns do in early gestation?
have mitotically active cells that migrate into trophoblastic shell
cells can then remain tehre or migrate into uterine arteries
lost during later pregnancy
what's another name or names for the trophoblastic shell?
maternal side of floor of placenta
what makes up the trophoblastic shell in developed placenta?
1. layer of syncytial trophoblast
2. several layers of cytotrophoblast cells and extracellular matrix from trophoblast
3. merged with chorionic plate at perimeter of placenta
4. directly attached to underlying endometrium or decidua basalis - have mixed uterine stromal cells and extravillous trophoblast cells at this juncture - trophoblast cells migratory here and may travel deep into uterus, living in decidua and myometrium
what's the basal plate?
refers to trophoblast shell and adjacent endometrium, the decidua basalis
what kind of extravillous trophoblast cells are in basal plate?
may be cytotrophoblast or syncytiotrophoblast
what is in large area between chorionic plate and trophoblastic shell?
highly branched villi
what's the relationship between the stem villi and villi?
need to figure this out - need pictures
what are terminal villi?
are finest diameter villi
what's another name for terminal villi?
free villi
what structures are contained within terminal or free villi?
loops of fetal capillaries next to surface of trophoblast cells
what kind of covering do all placental villi retain, regardless of their size?
complete covering of syncytial trophoblast
what's another name for placental macrophages?
Hofbauer cells
what are Hofbauer cells?
are placental macrophages
where are hofbauer cells or placental macrophages?
are in villus connective tissue in first trimester
what are contained within hofbauer cells or placental macrophages?
many pale vesicles
when do typical macrophages become prevalent in pregnancy?
later gestation
where is hCG produced?
cytotrophoblast cells
when do cytotrophoblast cells start producing hCG?
8 days after fertilization
what does hCG stand for?
human chorionic gonadotropin
what is hCG?
is an LH-like glycoprotein
what does hCG do?
supports corpus luteum until placenta developed enough to make enough progesterone to maintain uterus
what does the phrase "rescue of the corpus luteum" refer to?
refers to extension of lifespan of corpus luteum by hCG
what is the extension of the lifespan of corpus luteum by hCG referred to as?
"rescue of corpus luteum"
what are the basis of contemporary pregnancy tests?
detection of hCG in blood or urine
what cells make chorionic somatomammotropin, or human placental lactogen or hPL?
trophoblast cells
what's another name for chorionic somatomammotropin?
human placental lactogen or hPL
what's another name for hPL or human placental lactogen?
chorionic somatomammotropin
what's hPL stand for?
human placental lactogen
what hormones do trophoblast cells produce?
1. cytotrophoblast start making hCG
2. syncytial trophoblast makes hCG through end of gestation
3. hPL
4. placental corticotropin releasing hormone
6. progestins
7. estrogens
what structure of placenta produces hCG through gestation?
syncytial trophoblast
does production of hCG drop when corpus luteum dies?
no; is constantly produced by syncytial trophoblast
what's the interhemal barrier?
separates mom's and fetus's circulatory systems
in on villi
composed of several layers
also called interhemal membrane
what's another name for the interhemal barrier?
interhemal membrane
what are the layers of the interhemal barrier or interhemal membrane?
1. syncytial trophoblast
2. cytotrophoblast
3. trophoblast basal lamina
4. fetal connective tissue
5. capillary basal lamina
6. fetal endothelium
what's special about the syncytial trophoblast throughout gestation?
is fetal tissue that's in DIRECT contact with maternal blood in intervillous space
has microvilli with receptors and transport systems for metabolites in maternal blood
what's on apical surface of syncytial trophoblast?
microvilli with receptors and transport systems for metabolites in maternal blood
what kind of organelles are in syncytial trophoblast?
many golgi complexes
what are syncytial knots?
are cluster of syncytial trophoblast nuclei
are syncytial trophoblast cells capable of mitosis?
what's cytotrophoblast layer of interhemal barrier look like?
early gestation- is continuous layer
later gestation - number of cells declines
cytotrophoblast cells are capable of mitosis; are stem cell poulation from which syncytial trophoblast cells are formed throughout pregnancy
what kind of cells form most of epithelium of villi in later pregnancy?
syncytiotrophoblast because cytotrophoblast layer just disappears as gestation wears on
what's the trophoblast basal lamina like?
is typical basal lamina along basal surface of trophoblast
where's fetal tissue in relation to villi and interhemal exchange areas?
abundant in villi usually, but almost nothing where there's interhemal exchange
what's the capilary basal lamina like, where is it?
is typical basal lamina along basal surface of fetal endothelium
what kinds of cells do fetal endothelium form?
continuous capillaries
what are important fetal membranes to know besides the interhemal barrier?
nonvillous chorion or chorion laeve
which parts of the endometrium obliterate the uterine lumen eventually?
decidua capsularis and decidua parietalis - with capsularis being pressed against parietalis
what happens to intervening uterine eptihelium between decidua capsularis and decidua parietalis in later pregnancy?
is obliterated
what do trophoblast cells of chorion laeve do?
make peptide and steroid hormones
could be additional route of exchange tween fetus and mother
what's the vasculature of the smooth chorion like?
is avascular
where is amnion, what is in it?
surrounds fetus, contains amniotic fluid
what's vasulature of amnion?
is avasular like nonvillous chorion or chorion laeve
what's another name for chorion laeve in later gestation?
nonvillous chorion
what do the apical surfaces of the amniotic epithelial cells look like, and how are they oriented in relation to the fetus?
are cuboidal and oriented towards fetus
what is the chorioamnion?
is fusion of chorion and amnion
trophoblast cells can migrate upstream against maternal blood flow - when would there be a situation where they might go downstream in maternal blood flow?
small clumps of trophoblast breaks away from villi sometimes
enters maternal blood via uterine veins
usually lodge in lungs, but are not problem because they deteriorate
what is an ectopic pregnancy?
when blastocyst implants in abnormal location
what is gestational choriocarcinoma?
is an aggressive tumor of pregnancy-derived trophoblastic cells
is highly invasive and readily metastasizes
villi not formed
cytotrophoblast and syncytiotrophoblast present
responsive to chemotherapy