Lect 8. Fertilization and Implantation Flashcards
Entering the Oviduct
After ovulation the oocyte is technically in ____
the peritoneal cavity
Entering the Oviduct
To enter the uterine tube, ____ “sweep” follicular fluid and oocyte to enter infundibulum and ampulla of oviduct and toward the uterus
fimbriae of the oviduct
Entering the Oviduct
To enter the uterine tube, fimbriae of the oviduct “sweep” ____ to enter infundibulum and ampulla of oviduct and toward the uterus
follicular fluid and oocyte
Entering the Oviduct
To enter the uterine tube, fimbriae of the oviduct “sweep” follicular fluid and oocyte to enter ____ and toward the uterus
infundibulum and ampulla of oviduct
Entering the Oviduct
To enter the uterine tube, fimbriae of the oviduct “sweep” follicular fluid and oocyte to enter infundibulum and ampulla of oviduct and toward ____
the uterus
Entering the Oviduct
Approximately 1 % of spermatozoa ejaculated into the vagina make their way through ____
cervix
Entering the Oviduct
Contractions of _____ (2) propel spermatozoa closer to oocyte
uterus and uterine tube
Entering the Oviduct
→ IDENTIFY
Entering the Oviduct
→ IDENTIFY
Entering the Oviduct
→ IDENTIFY
Entering the Oviduct
→ IDENTIFY
Process of Fertilization
After several hours in the uterus and oviduct, spermatozoa become ___.
capacitated
Process of Fertilization
After several hours in the uterus and oviduct, spermatozoa become capacitated.
They undergo ____, releasing enzymes that assist them in passing through the zona pellucida.
the acrosome reaction
Process of Fertilization
After several hours in the uterus and oviduct, spermatozoa become capacitated.
They undergo the acrosome reaction
→ The role of acrosome reaction?
releasing enzymes that assist spermatozoa in passing through the zona pellucida.
Process of Fertilization
→ How many spermatozoa successfully pass through the zona pellucida?
A single spermatozoa successfully passes through the zona pellucida, fuses with oocyte and its nucleus enters the oocyte.
→ Fertilization has occurred!
When does fertilization occur?
When a single spermatozoa fuses with oocyte and its nucleus enters the oocyte.
Process of Fertilization
The oocyte releases ___ that make the zona pellucida impermeable and de- activate spermatozoa receptors.
This prevents polyspermy.
cortical granules
Process of Fertilization
→ Identify
→ Its role?
cortical granules
→ that make the zona pellucida impermeable and de- activate spermatozoa receptors.
→ prevents polyspermy.
Process of Fertilization
The secondary oocyte to complete the second phase of meiosis.
→ This creates ___
the haploid secondary oocyte and 2 additional polar bodies.
Process of Fertilization
Sperm penetration triggers ___
How does the fusion of pronuclei occur after fertilization?
Haploid female pronucleus and haploid male pronucleus each replicate their DNA, creating 2 chromatids for each chromosome
→ fuse to become a new diploid individual
Fusion of the Pronuclei
Pronuclei fuse to become ___
a new diploid individual
Fusion of the Pronuclei
Pronuclei fuse to become a new diploid individual; chromosomes arrange themselves in (1)____ (which phase?) and single-celled zygote undergoes (2)___ and its first mitotic division
- metaphase
- cleavage
Fusion of the Pronuclei
Pronuclei fuse to become a new diploid individual; chromosomes arrange themselves in metaphase and ____ undergoes cleavage and its first mitotic division
single-celled zygote
Fusion of the Pronuclei
Pronuclei fuse to become a new diploid individual; chromosomes arrange themselves in metaphase and single-celled zygote undergoes cleavage and its first ____
mitotic division
Fusion of the Pronuclei - Pronuclear stage
→ Identify
Zygote and Morula
Cleavage creates (1)____ after about 30 hours and (2)___ after about 40 hours
- 2-celled zygote
- 4-celled zygote
Zygote and Morula
Cells of zygote undergo (1)___, keeping inner cells away from external environment
compaction
Zygote and Morula
Cells of zygote undergo compaction, keeping ____ away from external environment
inner cells
Zygote and Morula
Cells of zygote undergo compaction, keeping inner cells away from __
external environment
Zygote and Morula
Cells of zygote undergo compaction, keeping inner cells
away from external environment
→ during divisions, do cells enlarge?
NO!
Zygote and Morula
Cells of zygote undergo compaction, keeping inner cells
away from external environment
→ during divisions, cells do not enlarge, so the whole assembly is roughly same size as ____
the original secondary oocyte
Zygote and Morula
After 3 days zygote has about 16 cells and is called (1)____,
morula
Zygote and Morula
What does a morula contain?
inner cell mass and outer cell mass
Zygote and Morula
→ identify
Blastocyst
After 4 days, (1)____ deteriorates, allowing fluid to penetrate morula
zona pellucida
Blastocyst
After 4 days, zona pellucida deteriorates, allowing fluid to penetrate ____
morula
Blastocyst
After 4 days, zona pellucida deteriorates, allowing fluid to penetrate morula
→ fluid forms (1)___ and the whole cell cluster is now called (2)___
- blastocyst cavity
- blastocyst
Blastocyst
After 4 days,
(1)____ is now called the embryoblast and will create (2)___
- Inner cell mass
- the structures of the embryo
Blastocyst
After 4 days,
(1)____ called trophoblast will become (2)____ surrounding and nurturing the developing embryo and fetus
- Outer cell mass
- the placenta and membranes
Blastocyst
After 4 days,
Outer cell mass called trophoblast will become the placenta and membranes surrounding and nurturing ___
the developing embryo and fetus
Name of this cell?
Early blastocyst
Blastocyst
→ identify
Name of this cell and identify
Implantation
→ Where does fertilization occur?
Fertilization occurs in the ampulla of oviduct
Implantation
Fertilization occurs in the ampulla of oviduct
→ ___ has entered the uterus after 4 days
blastocysts
Implantation
If the developing embryo implants in the uterus
→ trophoblast cells begin producing ____
human chorionic gonadotropin (hCG)
Implantation
If the developing embryo implants in (1)___
→ (2)___ begin producing human chorionic gonadotropin (hCG)
- the uterus
- trophoblast cells
Implantation
3 roles of human chorionic gonadotropin (hCG)
- prevents corpus luteum from degenerating
- keeps progesterone levels high
- preventing degeneration of the follicular layer of endometrium
Implantation
3 roles of human chorionic gonadotropin (hCG)
- prevents ___ from degenerating
- keeps ___ levels high
- preventing degeneration of ___ of endometrium
- corpus luteum
- progesterone
- the follicular layer
Implantation
3 roles of human chorionic gonadotropin (hCG)
- prevents corpus luteum from ___
- keeps progesterone levels ___ (low/high)
- preventing degeneration of the follicular layer of ___
- degenerating
- high
- endometrium ((en-doh-MEE-tree-um) The layer of tissue that lines the uterus.)
Implantation
→ IDENTIFY
What’s happening here?
Ovulation
What does a pregnancy test measure?
levels of human chorionic gonadotropin (hCG) in urine
Eventually the placenta will produce enough ___ to maintain pregnancy
progesterone
Embryoblast and Trophoblast
Blastocyst has 2 distinct cell populations
→ What are they?
- Embryoblast (inner cluster of cells)
- Trophoblast (outer cell layer)
Embryoblast and Trophoblast
The role of trophoblast
nourishing and protecting growing fetus
Embryoblast and Trophoblast
As blastocyst implants into ____ , around day 7, trophoblast differentiates into 2 different regions
follicular layer of the endometrium
Embryoblast and Trophoblast
___ is layer of cuboidal cells surrounding developing the embryo
Cytotrophoblast
Embryoblast and Trophoblast
At the place where the blastocyst implants group of (1)___ begin burrowing into endometrium
→ in the process, they lose (2)____ and form a large multi-nucleated mass, syncytiotrophoblast, that burrows into endometrium
- trophoblast cells
- cell membranes
Embryoblast and Trophoblast
At the place where the blastocyst implants group of trophoblast cells begin burrowing into endometrium
→ in the process, they lose cell membranes and form a large multi-nucleated mass called ___
syncytiotrophoblast
Embryoblast and Trophoblast
→ IDENTIFY
Embryoblast and Trophoblast - day 7
→ IDENTIFY
Expansion of the Syncytiotrophoblast
By day 8, blastocyst migrates deeper into the endometrium; the deeper it goes the more it encounters ____
uterine glands and vessels
Expansion of the Syncytiotrophoblast
Hypoblast and epiblast have formed (1)___ with a tiny (2)___ developing within the epiblast layer
- bilaminar embryo
- amniotic cavity
Expansion of the Syncytiotrophoblast
__and__have formed bilaminar embryo with a tiny amniotic cavity developing within the epiblast layer
Hypoblast and epiblast
Expansion of the Syncytiotrophoblast
Hypoblast and epiblast have formed bilaminar embryo with a tiny amniotic cavity developing within ___
- the epiblast layer
Expansion of the Syncytiotrophoblast - DAY 8
→ IDENTIFY?
Implantation and the Trophoblast
As syncytiotrophoblast erodes glands and vessels in endometrium, small, blood-filled ____ form in syncytiotrophoblast, around 9 days into development
trophoblastic lacunae
Implantation and the Trophoblast
As ___ erodes glands and vessels in endometrium, small, blood-filled trophoblastic lacunae form in syncytiotrophoblast, around 9 days into development
syncytiotrophoblast
Implantation and the Trophoblast
As syncytiotrophoblast erodes glands and vessels in endometrium, small, blood-filled trophoblastic lacunae form in syncytiotrophoblast, around 9 days into development
→ Allows ___ to reach and nurture developing embryo; however, it is not very efficient yet since there is no organized flow
maternal blood
Implantation and the Trophoblast
___ has formed to separate cytotrophoblast on one side from the bilaminar embryo and primary yolk sac on the other
Extraembryonic mesoderm
Implantation and the Trophoblast
Extraembryonic mesoderm has formed to separate ___ on one side from the bilaminar embryo and primary yolk sac on the other
cytotrophoblast
Implantation and the Trophoblast
Extraembryonic mesoderm has formed to separate cytotrophoblast on one side from (1)___ and (2)___ on the other
- the bilaminar embryo
- primary yolk sac
Implantation and the Trophoblast - DAY 9
→ identify
Formation of the Chorionic Cavity
During 10th to 12th days after fertilization
→ ____ enlarge to surround the embryo as it moves even deeper into the endometrium
Trophoblastic lacunae
Formation of the Chorionic Cavity
During 10th to 12th days after fertilization
→ Fluid-filled spaces (Trophoblastic lacunae) start to develop in the extraembryonic mesoderm
→ will form ___
extraembryonic coelom
Formation of the Chorionic Cavity
By day 13, ___ has begun to send cellular projections into the syncytiotrophoblast
cytotrophoblast
Formation of the Chorionic Cavity
Extraembryonic coelom enlarges, separates (1)___
→ space is called (2)____.
- the embryo and cytotrophoblast
- chorionic cavity
Formation of the Chorionic Cavity
What is chorion?
Outer lining of cytotrophoblast, syncytiotrophoblast, and trophoblastic lacunae
Formation of the Chorionic Cavity
Outer lining of cytotrophoblast, syncytiotrophoblast, and trophoblastic lacunae is called ___
chorion
Connecting Stalk and Umbilical Cord
By 14th day, (1)____suspended within the chorionic cavity by its attachment to the bilaminar embryo; remnants of primary yolk sac are located on opposite side of (2)___
- secondary yolk sac
- cytotrophoblast
Connecting Stalk and Umbilical Cord
By 14th day, secondary yolk sac suspended within (1)___ by its attachment to the bilaminar embryo
→ remnants of (2)___ are located on opposite side of cytotrophoblast
- the chorionic cavity
- primary yolk sac
Connecting Stalk and Umbilical Cord
By 14th day, (1)____suspended within the chorionic cavity by its attachment to the bilaminar embryo; remnants of primary yolk sac are located on opposite side of (2)___
- secondary yolk sac
- cytotrophoblast
Connecting Stalk and Umbilical Cord
day 14
Bilaminar embryo is suspended within the chorionic cavity by (1)____ of extraembryonic mesoderm
→ connection between embryo and trophoblast will become (2) ___
- connecting stalk
- umbilical cord
Connecting Stalk and Umbilical Cord
Bilaminar embryo is suspended within the chorionic cavity by connecting stalk of (1)____
→ connection between (2)____ will becom the umbilical cord
- extraembryonic mesoderm
- embryo and trophoblast
Formation of the Chorionic Cavity - day 10 - 12
→ IDENTIFY?
Formation of the Chorionic Cavity - day 13
Connecting Stalk and Umbilical Cord - DAY 14
→ IDENTIFY
Placenta
What will create secondary villi?
Extraembryonic mesoderm that underlies cytotrophoblast will invade the core of each villus to create secondary villi
Placenta
Blood vessels will develop within extraembryonic mesoderm to connect villi, connecting stalk, and the embryo; once blood vessels present within villi, they are termed ___
tertiary villi
Placenta
What will create tertiary villi?
Blood vessels will develop within extraembryonic mesoderm to connect villi, connecting stalk, and the embryo
→ once blood vessels present within villi, they are termed tertiary villi
Placenta
Syncytiotrophoblast leaves ___ that anchor the placenta to the uterus
placental lobes, cotyledons
Placenta
The role of cotyledons
placental lobes that anchor the placenta to the uterus
Placenta
___ leaves placental lobes, cotyledons, that anchor the placenta to the uterus
Syncytiotrophoblast
Placenta
In each cotyledon, cytotrophoblast leaves gaps for uterine arteries and veins to reach ___; these fill with maternal blood and closely associate with tertiary villi
intervillous spaces
Placenta
In each cotyledon, cytotrophoblast leaves gaps for (1)___ to reach intervillous spaces
→ these fill with (2)____ and closely associate with tertiary villi
- uterine arteries and veins
- maternal blood
Placenta
In each cotyledon, cytotrophoblast leaves gaps for uterine arteries and veins to reach intervillous spaces
→ these fill with maternal blood and closely associate with ___
tertiary villi
Placenta
Placenta is the whole assembly of ___ and ____
trophoblast
intervillous spaces
Placenta
→ Identify
Placenta
→ IDENTIFY
Placenta
→ IDENTIFY
