Physiology 3120 Lecture Notes - Lecture 3: Syncytiotrophoblast, Umbilical Artery, Chorionic Villi

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Regnault Lecture 3
Sperm Transport (fast)
250million sperm get into vagina
Fewer make it to uterus
Even fewer into ampulla of fallopian tube  FERTILIZATION
Fertilized Zygote Transport (slow)
-fertilized zygote travels from fallopian tube ampulla to isthmus to get implanted in uterus
-estrogen primary role of follicle maturation to resume meiosis I
-estrogen also needed for uterine cell proliferation and progesterone receptors
-estrogen increases growth and activity of cilia
-estrogen allows contractions of smooth muscles and myometrium to aid sperm movement
(next slide)
-estrogen decreases viscosity of mucus so that sperm can flow more easily
-estrogen increases glycogen to increase lactate conc ie: contributing to decreased pH  sperm
protected by alkaline coat
-muscular contractions of walls of uterus/fallopian tubes due to adrenergic receptor
-production of adrenergic receptors stimulated by estrogen
RMR capacitation starts in male reproductive tract and completes in female reproductive tract
into mature, functional sperm
-acrosomal membrane fuses with PM of sperm head to allow hydrolytic enzymes within
acrosome to degrade zona pellucida for sperm entry
-dilutes sperm at ejaculation, activates motility and provides nutrients for sperm metabolism
-summary of next few slides
-circle is where acrosomal reaction occurs
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-bottom picture shows sperm head PM fusing with oocyte PM to release its contents into
oocyte cytoplasm (green)
-THIS is acrosomal reaction  release enzymes to degrade granulosa cells and zona pellucida so
sperm can get in
-zona pellucida has ZP3R which binds to ZP3 protein on sperm head
-ZP3 is main ligand since initiates primary sperm binding
-so now sperm within zona pellucida borrowing path using whip-like movement
-fertilin allows sperm and egg PM to fuse which triggers Ca influx that allows sperm nucleus to
be pulled into egg
-cortical reaction occurs when sperm nucleus pulled in
-hardens zona pellucida and degrades ZP3 receptors so no other ZP3 proteins on other sperm
can bind
-meiosis II completed with release of second polar body ie: haploid female gamete now
-simultaneously, male chromatin decondenses to make male pronucleus ie: haploid male
gamete
-pronuclei of male and female gametes combine chromosomes to form diploid zygote
-finally, diploid zygote undergoes mitosis to divide and grow
RMR from previous lecture where end of meiosis II produces one viable ovum and other 3
degraded
1n, 1c  haploid with one copy of chromosome ie: |
-mitosis as move towards each other so 1n, 2c  still haploid but with 2 copies of chromosome
ie: X
-nuclear membranes disintegrate to get combine two haploid cells so 2n, 4c  diploid with 4
chromosome copies
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