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oogenesis
formation and maturation of female gametes
when does oogenesis start
prenatal stages
oogonia multiply by
mitosis until near birth
two stages of meiotic divisions
meiosis 1 and meiosis 2
meiosis 1
arrested (stop developing) at late prophase
dictyate oocyte
arrested oocyte
no oocyte
mature before puberty
growth and maturation occurs
in cycles after puberty
only oocytes in dominant follicles
mature
follicular development occurs in
waves/cohorts
The zona pellucida develops when
when oocytes grows
zona pellucida
outer membrane of the follicle
what hormone is produced by the mature follicle
estrogen
1st follicle, secondary follicle, tertiary follicle, graffian follicle
antrum forms as
dominant follicles emerge
ovulation is induced by what hormone
LH
meiosis 2 is arrested at
metaphase
meiosis 2 only occurs of
fertilization occurs
meiosis 1 yields
secondary oocyte and 1st polar body
meiosis 1 occurs before
ovulation
Ater Estrogen triggers LH what happens to oocytes in Meiosis 1
oocytes are freed into follicular fluid and meiosis 1 resumes
how long does it take for oogenesis to complete
anywhere between 12 to 50 years on cyclic basis from puberty to menopause
each primary oocyte yields how many ovum and polar bodies
1 cytoplasm rich ovum and 3 cytoplasm poor polar bodies that disintegrate
Meiosis 1 occurs in what phase
prophase 1
What phase does meiosis 2 occur
Metaphase
What causes follicles to develop
LH
Proteolytic enzymes do what
Weaken the follicular walls
Ovulation results in
The release of the secondary oocyte, follicular fluids, and cumulus cells
Stigma occurs where
Rupture site
An oocyte moves where
Down the oviduct to ampullary-isthmic junction for fertilization
Peristalsis
Muscle contraction
What slows down and hastens transport
Estrogen slows transport
Progesterone hastens transport
Where do sperm transport
Bovine uterus and oviduct (4-16hrs)
First barrier
Cervix that filter dead sperm
Second barrier to the AI junction
Uterotubal junction
Filter sperm and serve as a reservoir for slow continuous release
Lower isthmus
Hormones that speed sperm transport
Prostaglandin and estrogen
Fertilization occurs in
The ampullary-isthmic junction
The site of fertilization
Oviduct
Fertilization
Formaction of zygote
Enzymes of sperm head allow
For penetration of cumulus and corona radiata cells
What facilitate enzymatic activity
Capacitation and acrosome
Sperm head sticks to
The zone pellucida
What allows zona pellucida penetration
Acrosome enzymes
Zona reaction
Prevents other sperm from crossing the zone pellucida
During fertilization sperm enters
The vitelliene membrane by phagocytosis
The second block against other sperm participating in fertilization
Vitelline block
When meiosis 2 resumes what happens
The 2nd polar body is extruded and the female pronucleus forms
Sperm looses its tail and the male pronucleus forms
Syngamy
Merging of pronucleus during fertilization
What happens for fertilization to be complete
Zygote
Polyspermy
Fertilization by 2 or more sperm that results in embryo loss and occurs in heated or aged secondary oocytes
The two barriers to polyspermy
Zona rection and vitelline block
zygote
one cell embryo
spontaneous vs reflex ovulation
spontaneous- ovulating whether they are mating or not
reflex- ovulating only when they mate
cows do not ovulate until…
they are out of estrus