Fertilization Flashcards
which female animals have semen depositing in the vagina?
ruminants, primates, rodents, cats
which female animals have semen depositing in the cervix?
pigs, equids
which female animals have semen depositing in the uterus?
dogs
the __ is a major barrier to sperm transport (except pigs and dogs)
cervix
cervical sperm transport has a 1. __ phase characterized by injection to uterus by ejaculatory force and a 2. __ phase where the sperm swim upgrade through channels in cervical crypts to avoid retrograde mucous flow
rapid, slow
once in the uterus, sperm travel __ towards the __and accumulate there binding to epithelial cells until released into the __
anterograde, UTJ, oviduct
define sperm capacitation and where it takes place
sperm capacitation is the physiologic changes that sperm undergo in the female tract to gain the capacity to undergo the acrosome reaction and usually takes place in the uterus or uterine tube of the female tract
Sperm undergo capacitation to prepare for __ and undergo the acrosome reaction once bound to the __ of the oocyte
fertilization, zona pellucida
capacitation of ejaculated sperm involves __ being added to sperm and blocking calcium transport, then in the capacitated sperm __ is removed and sperm is competent to bring calcium inside
caltrin
define the acrosome reaction.
release and exposure of acrosomal contents
steps of the acrosome reaction
- sperm binds to zona pellucida via ligand receptor interaction (ZP3)
- receptor on sperm triggers calcium influx
- intracellular calcium rises causing membrane fusion
- outer acrosomal and sperm cell membrane fuse
- resulting pores permit escape of soluble acrosomal contents
- exposure of inner acrosomal membrane which binds to ZP2
sperm penetration of the zona pellucida depends on __ and __
acrosin- digested pathway and hyperactivated motility (helps get the sperm through the zona)
briefly describe sperm - egg binding
- entire sperm enters perivitelline space and motility diminishes
- sperm binds to oocyte cell membrane
- sperm ligand binds to oocyte surface receptor triggering depolarization and cortical reaction
- the cortical reaction (exocytosis) releases proteases that alter the zona structure making it resistant to acrosin digestion (blocks polyspermy)
when the sperm head first enters the ooplasm, it immediately__ and protamines are replaced by __ resulting in the haploid genome becoming organized into chromosomes
swells, histones
the male pronucleus is the __and is surrounded by a pronuclear envelope and __ as it moves towards the center of the ovum ready for __ of mitosis
enlarging sperm head, microtubules, metaphase
After kicking out the second polar body, the remaining haploid genome forms the ___ and moves to the center of the ovum where it is usually __ than the male pronucleus
female pronucleus, smaller
Syngamy
when the 2 pronuclei reach the center, the pronuclear envelopes disappear and the two genomes become one. The chromosomes with duplicated chromatids line up on the metaphase plate for the first mitosis
the morula undergoes __ between 8-16 cells by forming tight junctions with cell adhesion molecules between adjacent cells so that cell boundaries become difficult to see
compaction
after the morula, a __ forms and the ICM and __ will continue to multiply while blastocoel fluid accumulates
blastocyst, trophoblast
a blastocoel fluid accumulates in the blastocyst the __ streches and thins until it ruptures and __
zona pellucida, escapes