9/15 Embryonic Development Wks 1-3 - Dennis (Completed) Flashcards
Differentiate Oocyte from Sperm? 4
Sperm:
Highly motile
23X or 23Y
Small
Oocyte:
immotile
23X
Massive
When does a primary Oocyte mature into a secondary Oocyte? 5
Primary Oocytes mature after puberty once the follicle is matured
What state are secondary Oocytes suspended in prior to ovulation? 5
The secondary Oocyte begins it’s 2nd meitotic division, but stops at metaphase
How many primary Oocytes are present at birth? How many secondary Oocytes are actually ovulated? 5
2 million primary Oocytes at birth
400 secondary Oocytes actually ovulated
What cells surround the Oocyte and are responsible for folliculogenesis? 6
Granulosa cells
What granulosa cells are present within a follicle? 6
Cumulus oophorous
Mural granulosa cells
Corona Radiatia
What anchors the primary oocyte to the wall of the follicle? 6
Cumulus oophorous granulosa cells
What lines the wall of the follicle? 6
Mural granulosa cells
What cell type is firmly anchored to the zone pellucida? 6
The corona radiata (granulosa cells)
What is the Zona pellucida? 6
a thick layer of glycoproteins that are deep to the corona radiata
From superficial to deep what are the layers/components of a secondary oocyte? 9
Corona radiata > Zona pellucida > perivitelline space > perivitelline membrane > PM of oocyte > cytoplasm of oocyte >
Where is the nucleus of a sperm found? 8
Head
What provides motility to the sperm? 8
Tail
What covers the head of the sperm? Describe it. 8
The acrosome
cap-like organelle containing enzymes
What is the role of the acrosome? 8
disperese the corona radiata (follicular cells)
penetrates the zona pellucida
What is the cortical reaction? 10
Reaction that takes place to allow sperm entrance into the PM/cell
Walk-through of cortical reaction. 10
cortical granules attach to microvilli at PM surface
reaction between cortical granules and water produces hydrogen peroxide (facilitated by Udx1)
envelope open, sperm gamete can enter
What does fertilization of an oocyte induce in the oocyte? 11
completion of meiosis II
What is a zygote? 11
when the female and male pronuclei fuse forming a diploid chromosome aggregation of 46 chromomsomes
What refers to the failure of chromosomes to separate during early cleavage? 12
Nondisjunction (a part of mosaicism)
What is one example of mosaicism? 12
trisomy 21
individual is referred to as a mosaic
What occurs 30 hours after fertilization? 13
blastomeres are produced (numerous, but small)
What happens at the 9 cell stage? 13
compaction
What happens at the 12-32 cell stage (day 4)? 13
developing human referred to as a morula
walk-through of Blastogenesis. 14
Blastocyst forms cavity in uterus
division into trophoblast and embryoblast layer
after 2 days zona pellucida degenerates and the blastocyst is “hatched”
What is contained within a blastocyst? 14
the embryo and its membranes
What’s occuring cryopreservation of Embryos? 18
early embryos preserved in liquid nitrogen
4-8 cell embryo/blastocyst transferred to uterus
Whats occuring during intracytoplasmic sperm injection? When would this be done? 18
sperm is injected straight into a mature oocyte
done when few sperm is available
What is occuring in assisted IVF? 18
several oocytes & sperms placed into uterine tubes laparoscopically
Where does fertilization occur? 18
in the ampulla
What are the causes of spontaneous abortion? 19
inadequate production of progesterone and estrogen from corpus luteum
chromosome abnormalities
What is an ectopic pregnancy?
Where does it occur? 20
the blastocyst becomes implanted outside of the uterine cavity
oviduct
ampullary region
What is the Syncytiotrophoblast? 21
multinucleated protoplasmic mass w/ no cell boundaries
forms the outer layer
What is the function of the Syncytiotrophoblast? 21
produces digestive enzymes that erodes the endometrium allowing the blastocyst to burrow
What is the Cytotrophoblast? What is its function? 21
The inner layer of the blastocyst (embryo)
produces chorionic villi
What does the hypoblast give rise to? 22
an inner layer of cuboidal cells that gives rise to the endoderm
What does the epiblast give rise to? 22
layer of columnar cells that gives rise to the embryo proper
What gives rise to the embryonic portion of the placenta? 23
chorion
What serves as a site for early blood cell and vessel formation? 23
yolk sac
What thin layer of cells encloses the epiblast and holds the amniotic fluid and the embryo? 23
Amnion
At what week does the amniotic cavity form? 24
2nd week
How does the amnion form? 24
fluid collects between the epiblast and trophoblast cells
this causes the epiblast cells to expand toward the embryonic pole forming the amnion
what’s the name of the cells that line the yolk sac? 25
Heuser’s membrane
How does the primary yolk sac come to be? 25
cells from the hypoblast creep along the inner surface of the blastocyst cavity
Once the primary yolk sac is formed, what is found between Heuser’s membrane and the cytotrophoblast? 25
extraembryonic mesoderm
What gives rise to the extraembryonic mesoderm? 25
hypoblast & primary yolk sac
What occurs at day 12? 26
primary yolk sac degenerates and migrating hypoblast cells forming a secondary yolk sac
What is formed by the splitting of the extraembryonic mesoderm into two layers?
The chorionic cavity
Why does the chorionic cavity need to be formed? 26
because it separates the embryo, amnion, and yolk sac from the outer wall of the blastocyst
With the formation of the chorionic cavity what do we begin to referring to the outer wall of the blastocyst as? 26
referred to as the chorion
What tissue makes up the amnion/chorion? 26
extraembryonic ectoderm
mesoderm
What tissue makes up the yolk sac? 26
extraembryonic endoderm
mesoderm
What tissue makes up the chorion? 26
extraembryonic mesoderm
By day 13 where is the disc (embryo) located? 27
the disc is suspended in the chorionic cavity via a connecting stalk (extraembryonic mesoderm)
Walk-through, Trophoblast to embryo in middle of chorionic cavity. 28
Trophoblast differentiates into cytotrophoblast and syncytiotrophoblast
implants into the uterine endometrium
amniotic cavity forms and the syncytiotrophoblast expands
cells migrate from hypoblast to form Heuser’s membrane (primary yolk sac)
syncytiotrophoblast surrounds entire embryo
extraembryonic mesoderm forms and splits into two layers forming the chorionic cavity
trophoblast lacunae anastomose with maternal blood sinusoids
migration of cells (again) from hypoblast to form secondary yolk sac (primary yolk sac degrades)
embryo proper chilling in chorionic cavity connected by extraembryonic mesoderm connecting stalk
What is a hydatidiform mole? 29
an abnormal blastocyst that has a continued trophoblast development
What is a partial hydatidiform mole? 29
some embryonic development
triploid: 69, XXX, 69 XXY, 69 XYY
What is a complete hydatidiform mole? 29
No embryonic development
oocyte missing female pronucleus w/ duplicate male pronucleus
What makes up the endoderm of the umbilical vesicle? 30
hypoblast
What is gastrulation? 31
cells migrating from the epiblast to form the primary germ layers (all adult structures)
What signals the beginning o gastrulation? 31
formation of the primitive streak (thin depression of surface of epiblast)
What do cells that displace the hypoblast become? 32
embryonic endoderm
What do cells that remain in the epiblast become? 32
embryonic ectoderm
What do cells that remain in between the hypoblast and epiblast become? 32
embryonic mesoderm
What is a teratoma? 36
A tumor that arises from primordial germ cells (migratory cells that populate the gonads)
Containts multiple cell types
What tissue is the notochord derived from? 38
mesoderm
What does the notochord become in the adult? 38
spinal cord & CNS
What does endoderm give rise to? 40
epithelial linings of respiratory and digestive tracts
glands of GI tract, liver, and pancreas
What does ectoderm give rise to? 40
forms epidermis of skin
CNS/PNS
eyes/middle ear
What occurs during Neurulation? 41
process by which the notochord induces the overlying ectoderm to become a neural plate
What does the mesoderm give rise to? 42
skeletal muscles
blood cells
lining of BVs
CV system
trunk CT
serosal linings of all body cavities, visceral sm coats
