The First Week (Exam 1) Flashcards
How many sperm will fertilize a secondary oocyte
1
Will the oocyte lose the zona pellucida when ovulated
no
What is the corona radiata a remnant of
follicular cells that surround the oocyte
What is the first thing that the sperm will interact with during fertilization
corona radiata
How will the sperm get through the corona radiata
dump enzymes from its acrosome to penetrate this layer
What is the next step in fertilization after the sperm has penetrated corona radiata
has to cross the zona pellucida
Binding to the zona pellucida is what
species specific
After the sperm crosses through the zona pellucida, what occurs
the zona reaction
What is the zona reaction
the oocyte will release enzymes from lysosome that will block other sperm from entering
What occurs after the zona reaction
sperm has to cross plasma membrane
What will occur as a response to fusion of the sperm and oocyte cytoplasms
cortical reaction
What does the cortical reaction result in
preventing further sperm from entering to ensure that only one sperm fertilizes an oocyte
When will the second meiotic division of an oocyte occur
after fertilization
When sperm cell membrane dissociates, what does the sperm form
male pronuclei
What does the oocyte form in response to the male pronuclei
female pronuclei
After fertilization, when will the first division occur
when the male pronucleus is broken down
What are the flow of events that occur during fertilization
sperm passes through corona radiata
binding to zona pellucida (zona reaction occurs)
fusion of oocyte and sperm plasma membrane (cortical reaction occurs)
second meiotic division of oocyte and formation of male and female pronuclei
What are the results of fertilization
restoration of a diploid genome
genetic sex of the embryo is identified
cleavage is initiated
How do contraceptive pills work
contain estrogen and progesterone
inhibit the secretion of FSH and LH from pituitary, blockign follicle maturation and ovulation
effects on the uterus include reduced endometrial proliferation and secretion of thick cervical mucus
What birth controls will alter the progesterone curve
Depo, Plan B, RU-486
What is Depo-provera
progesterone analog
What is Plan B
Levonorgestrel
What is RU 486
an antiprogesterone
What changes occur to the zygote the first week after fertilization
-cleavage
-no growth in size
but increase in cell number
-remains in zona pellucida
Where do the cell divisions occur during cleavage
as the cell transverses the uterine tube
What are the small cells in cleavage called
blastomeres
What is a morula
once the cell has 16-32 cells
raspberry shaped ball of cells
What occurs during compaction
cells get closer together and increase cell contact
increase number of gap junctions between cells
nucleus is shifted to the center (determines polarity)
When is the blastocyst formed
First week
How is the blastocyst formed
cells begin to cluster on one side of the cell and around the outside edges
(creates outside cells and inner mass)
What are the different parts of the blastocyst
Inner cell mass
Outer cell mass
Blastocyst cavity
What is the inner cell mass called in a blastocyst
embryoblast
What is the outer cell mass called in a blastocyst
trophoblast
What is the time it takes from ovulation to implantation
6-7 days
What type of epithelium will surround an embryo after implantation
uterine epithelium will invade and be enclosed by
What is an ectopic pregnancy
pregnancy that occurs anywhere but the uterus
What are the risks of an ectopic pregnancy
high risk for rupture and death
What is placenta previa
abnormal placental implantation within the cervix
Are placenta previa pregnancies viable
yes
What is placental abruption
the placenta detaches from the uterus
What are the risks of placental abrupton
increased bleeding risks for mom
loss of blood supply to baby
What is placental accreta
when the placenta overgrows, takes over, the embryo does not develop
What are the risks to mom with placental accreta
bleeding risk
How long can sperm survive for
48 hours
the ovulated oocyte is only viable for how many hours
24 hours
Where does fertilization occur in the uterine tube
ampulla
Of the 300 million sperm deposited into the female reproductive tract how many make it to the egg
0.0001%
Passageway of the sperm through the corona radiata occurs through what reaction
acrosome reaction
How does the sperm cross the zona pellucida
releasing more acrosome enzymes
Fusion of the sperm to the oocyte causes what
the zona reaction
What does the zona reaction result in
altering the sperm receptors and prevents additional sperm from binding to the zona pellucida
Fusion through the plasma membrane results in what reaction
cortical reaction
What occurs during the cortical reaction
oocyte releases lysosomal contents to make membrane impenetrable to other sperm
What occurs during growth of pronuclei
replication of DNA
What is the name of an oocyte with two pronuclei
ootid
What is EPF
Early Pregnancy Factor
What is early pregnancy factor secreted by
trophoblast cells and appears in maternal blood 24-48 hours after fertilization
What can EPF used for
pregnancy tests during first 10 days
When does cleavage start in a zygote
within 24 hours
When does compaction occur
after 3 divisions
The cells of the morula give rise to what
all membranes and the fetal placenta
When does the morula enter the uterine cavity
day 4
What causes the morula to become a blastocyst
by taking up fluid and forming a blastocyst cavity
What events occur during implantation
dissolution of the zona pellucida
adhesion of blastocyst onto endometrium
trophoblastic penetration and spread into endometrium
migration of blastocyst into endometrium
What percent of pregnancies result in ectopic pregnancies
2%
where do 95% of ectopic pregnancies occur
in the uterine tube
What percentage of zygotes, morulae, and blastocysts spontaneously abort
45%
