Fert/Gast Flashcards
haploid cells can undergo __________ which is the fusion of nuclei of two sex cells
karyogamy
oocyte is ______ which the sperm is ________
immotile, highly motile
what is the sex chromosome constitution of gametes
sperm (23X or 23Y) and oocytes (23X)
At what point do primary oocytes stop being dormant and form mature, _______ oocytes
puberty, secondary
where does the secondary oocyte stop meiotic division
begins 2nd meiotic division but stops at metaphase II
how many oocytes do you have at birth? what kind are they?
2M, primary
How many oocytes remain at adolcescence
40k
About how many secondary oocytes form
about 400 form and are ovulated
the antral follicle is surrounded by what
granulosa cells
what are granulosa cells responsible for?
folliculogenesis
What anchors the primary oocyte to the wall of the follicle
cumulus oophorous
what line the wall of the follicle
mural granulosa cells
what are firmly anchored to the zona pellucida as well as being the closest layer to the oocyte
corona radiata
what is the thick layer of glycoproteins deep to the corona radiata
zona pellucida
what are the parts of the mature sperm
head (forms most of the bulk of the sperm and contains the nucleus)
neck (junction of head and tail)
tail (provides motility to the fertilization site)
what is the head of the sperm covered by
acrosome
what does the acrosome contain
enzymes that facilitate the dispersion of follicular cells of the corona radiata and penetration of the zona pellucida
are you born with all the oocytes you will have
yes
what causes the changes from primary oocyte to secondary
the stage of meiosis
what is the purpose of the follicle around the oocyte
protect and support the oocyte
what is the space that follicular fluid collects in the oocyte
antrum
how many polar bodies are produced? what are they
2, they are blebbing of the cytoplasm from the oocyte undergoing meiosis
what is the fate of the polar bodies
if the oocyte is fertilized the cytoplasm is resorbed
what are the steps of fertilization
- find egg
- attach to egg
- burrow through outer layer of oocyte
- fertilization occurs
what process does sperm have to undergo to bond to egg
capacitation
what causes the capacitation process
the environment of the vagina (acidic environment)
what does capacitation allow
the sperm to fuse with oocyte
what does izumo do
help recognize the egg and promote binding
where are izumo and juno/cd9 found
izumo on sperm; juno on egg
what is multiple sperm in the egg called
polyspermy
what ion is involved in the cortical reaction
Ca
what is the cortical reaction
the events following sperm and egg fusing that disallows other sperm from attaching and entering the cytoplasm
what stimulates oocyte to complete meiosis 2
fertilization
at what point is a zygote formed
when the male and female pronuclei allign at the metaphase plate
when zygote forms what becomes active
the zygotic genome
mosaicism is a result of
nondisjunction (where chromosome fails to separate)
repeated division of the zygote produces
blastomeres
when does cleavage begin
30 hours after fert
at 9 cell stage what happens
compaction (the zygote is the same size but contains more cells)
at 12-32 cells what is the human called
morula
at what point is the morula a blastocyst
when the blastocyst cavity appears
within the blastocyst there are 2 types of cells what are they
the embryoblast which makes up the clump of cell; trophoblast layer that makes up the perimeter
after how many days does the zona pellucida degenerate
2, this allow the hatching of the blastocyst
embryoblast cells are more/less totipotent than the trophoblast cells
more
what is the timeline of the first 5 days after fertilization
day 0 pronuclear day 1 2-cell day 2 4-cell day 3 8-cell day 4 morula day 5 blastocyst hatching
artificial methods of pregnancy
freeze eggs in N2, inject sperm into oocyte, assisted ivf (placement of sperm and egg in uterine tubes)
what helps prevent spontaneous abortion
progesterone
what is the common causes of spontaneous abortions
inadequate production of progesterone and estrogen; chromosomal abnormalities
what is the common location of the ectopic pregnancy
in the oviduct mainly in the ampullary region
what does ectopic pregnancy present like
appendicitis
placental previa
where the placenta attaches too close to the cervix
what two populations do the trophoblasts differentiate into
- syncytiotrophoblasts
- responsible for adhesion to endometrium
- release enzymes that break down endometrial wall and allow burrowing (decidualization) - cytotrophoblasts
- cells that surround the embryoblast inside the embryo
embryoblast splits into what two layers
hypoblast (primitive endoderm) - surrounds the epiblast inside the cell
epiblast - layer of cells deep to the hypoblast and gives rise to the embryo
what are the extraembryonic membranes?
- amnion - thin layer of cells that enclose the epiblast and holds amniotic fluid
- yolk sac - serves as site for early blood cell and vessel formation
- chorion-gives rise to the embryonic portion of the placenta
- allantois-where waste collects initial collection of germ cells as well
when does the amnion (amniotic cavity) form
beginning of second week
development of the yolk sac occurs when and forms what
day 8, primary yolk sac
what is heuser’s membrane
the cells that line the yolk sac
what fills the remainder of the space in the yolk sac
extraembryonic mesoderm (it arises from the hypoblast and primary yolk sac)
when does the primary yolk sac degrade
day 12; the secondary yolk sac forms
what new space forms by splitting the extraembryonic mesoderm into 2 layers
chorionic cavity
what is the chorion
separates the embryo with its attached amnion and yolk sac from the outer wall of the blastocyst
Amnion, definitive yolk sac, & chorion all become 2-layered
- Amnion/chorion = extraembryonic ectoderm & mesoderm
- Yolk sac = extraembryonic endoderm & mesoderm
- Chorion = extraembryonic mesoderm
day 13 the disc is suspended in the chorionic cavity by the
connecting stalk
what is the hydatidiform mole
abnormal blastocyst with continued trophoblast development
high levels of hcg, may produce choriocarcinoma
gastrulation
- process by which cells from the epiblast migrate to form the primary germ layers
- begins week 3 with the formation of the primitive streak
- once this has happened we have the trilaminar embryonic disc
epiblast gives rise to what layers
endoderm, mesoderm, ectoderm
where does the primitive streak move
caudal to cranial but doesn’t move all the way so cells need to move through the streak and migrate between the layers
teratomas
tumors from primordial germ cells which cause weird cell types to form where they wouldn’t normally
where does the notochordal process form
along the primitive pit; formation begins with cranial extension from the primitive node, forms a hollow tube called the notochordal process, grows cranially between ecto and endoderm before reaching the prechordal plate, by day 20 the notochordal process is complete
where is the notochord from
mesoderm
what does the notochord do
• Primary inductor in the early embryo: signaling required for
development of axial musculoskeleton & CNS
• Contributes to the nucleus pulposus in infants & children
