Lec 1 fert and embryology Flashcards
Describe the anatomy of the human ovum
blue space is perivitelline space
Haploid 23X
Describe the anatomy of the human sperm
Acrosome contains enzymes
Nucleus DNA 23X or 23Y
Neck is joining piece
Middle piece contains mito
What events happen in week 1
- Fertilization
- cleavage
- formation blastocyst
- formation embryoblast
- implantation
Where does fertilization occur?
Ampulla
what must happen for fertilization to occur?
Capacitation- glycoprotein coat and seminal plasmsa proteins removed from plasma membrane of sperm (acrosome reaction release enzymes)
After capacitation what happens?
passage of sperm through corona radiata with the release of Hyaluronidase
What allows the sperm to pass through corona radiata?
Hyaluronidase
After passage through corona radiata what happens?
penetration of zona pellucida- via release of
- esterases
- acrosin
- neuraminidase
After penetration of the zona pellucida?
Zona Reaction (when one sperm enters zona pellucida (zona reaction) causes mesh to be rigid
blocking polyspermy (Granules?)
After the zona reaction?
- Fusion of plasma membranes of oocyte and sperm
- Head and tail of sperm enter oocyte cytoplasm
(Sperm mitochondria do not enter)
what happens once sperm enters oocyte cytoplasm?
- completion of second meiotic division
- formation of male pronucleus
- fusion of male and female pronuclei= zygote
What are the results of fertilization?
approximately how long does fertilization take?
7 hrs
when does cleavage occur?
30 hr after fertilization
what happens during the beginning of cell cleavage?
- Once we have two cells the cells are called blastomeres
- the cells increase in number but decrease in size
- embryo size stays the same
- form a morula
cadherins help this
When does a morula form?
Around day 3
From morula to what?
Blastocyst (Day 5)
fluid enters and creates cavity
how many cells in a morula?
12-32 cells
Implantation happens when?
around day 6
What happens during day 5-7?
Early blastocyst to late blastocyst
- degenerating of zona pellucida
by day 7 it is gone (hatching of embryo)
What does the trophoblast form?
the inner cell mass?
Placenta
embryo
Blastocyst pic
after one week how many layers in the embryo?
one layer
the inner cell mass
Assisted reproductive technologies
- in vitro fertilization and embryo transfer
- cryopreservation of embryos
- intracytoplasmic sperm injection
(low sperm inject sperm into egg)
in vitro fertilization and embryo transfer overview
embryonic stem cells
from inner cell mass
(patients dont know they are pregnant at this stage so get from cryo)
pluripotent
Somatic nuclear transfer
Trophoblast gives rise to what?
- Cytotrophoblast
- syncytiotrophoblast
Cytotrophoblast is where and what does it do?
stem cell layer
mitotically active
Syncytiotrophoblast is where and what does it do?
- Multinucleated.
- releases proteolytic enzymes responsible for implantation
- releases chorionic gonadotropin hCG
(initial signal of pregnancy)
What happens in the first 10 days of implantation
immunosuppressant needs to be present
What is a hydatidiform mole?
abnormal trophoblastic proliferation; excessive amounts of hCG produced
2 types
Complete (Mole 1)
Partial (Mole 2)
Complete mole vs partial mole
C-fert of an empty oocyte, followed by duplication of the sperm.
or from fert of an empty oocyte by two sperm
P-fert of a normal oocyte by two sperm
(no polyspermy block)
(paternal fault)
clinical features of a hydatidiform mole
- vaginal bleeding
- pelvic pressure or pain
- enlarged uterus
- hyperemesis gravidarum (morning sickness) due to high hCG
What can form from a nonremoved hydatidiform mole?
Choriocarcinomas (3-5 percent)
-malignant tumor which develops from mole
spread to liver lung vagina intestine bone and brain.
Week 2 what structures are formed?
what do they arise from?
- Epiblast
- Hypoblast
Inner cell mass
What does Epiblast create?
- Ectoderm
- amnion
- amniotic cavity
What does Hypoblast create?
Endoderm
What is only present in week 2?
hypoblast
replaced in wk 3
Hypoblast to endoderm then to what?
Prechordal plate
primary and secondary yolk sac (umbilical vessel)
extraembryonic mesoderm
Extraembryonic Coelom vs somatic mesoderm vs splanchnic
Extraembryonic somatic mesoderm gives rise to what?
connecting stalk
chorion
extraembryonic splachnic mesoderm forms what?
Primitive blood
abnormal implantation
tubal pregnancy
placenta prev
quick explanation of gastrulation
primitive streak in caudal end invaginates as cells grow into eachother. they then get new signals and migrate to the hypoblast where they replace the hypoblast cells with true endoderm. Signals also tell cells in the middle to then change into the true mesoderm. we now have 3 layers
What gives rise to the diaphragm?
heart?
septum transversum
cardiogenic area
what is prechordal plate and cloacal membrane made of what do they become?
made of ectoderm and mesoderm
prechordal plate becomes mouth
cloacal membrane to urinary repro
sacroccoccygeal teratoma cause?
primitive streak from epiblast persisted and caused this
Notochord germ layer type?
mesoderm
Most important role of notochord?
induce the formation of neural plate and central nervous system (release sonic hedge hog)
chordomas
from the notochord slow growing aggressive neoplasm of bone
Mesoderm 3 layers with a notochord.
what are the three types of mesoderm?
paraxial
intermediate
lateral plate
Paraxial mesoderm creates what?
somites
