Fertilization Flashcards

1
Q

when is the best window for insemination?

A

6 hours after ovulation

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2
Q

can you inseminate prior tot he six hour window? after?

A

can inseminate before with lower chances of success but probably not after because ovulation will be finished

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3
Q

what scenario do you want in terms of sperm and the oocyte for insemination?

A

almost always want sperm waiting on the oocyte, not the other way around

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4
Q

define capacitation

A

the changes within sperm that confer upon the sperm the ability to acrosome react to the appropriate stimulus

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5
Q

what is the appropriate stimulus that causes sperm to acrosome react?

A

proximity to oocyte

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6
Q

describe the state of capacitation in mammalian sperm in the epidiymis

A

plasma membrane of epidydimal spermatozoa contains a complement of surface molecules that will combine with seminal plasma

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7
Q

describe the state of capacitation in mammalian sperm once ejaculated

A

the surace molecules in epidydimal sperm become coated with seminal plasma proteins that mask portions of the membrane molecules, DECAPACITATED

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8
Q

describe the state of capacitation on mammalian sperm when exposed to the female tract

A

when exposed to the female tract environment, the seminal plasma coatings and some of the surface molecules are moved, exposing portions of the molecules that can bind to the zona pellucida, CAPACITATED

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9
Q

is there change in sperm morphology in capacitation?

A

no, capacitated sperm will look the same as not capacitated sperm under a microscope

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10
Q

what characteristic of sperm changes during capacitation?

A

motility

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11
Q

describe the motility change in sperm during capacitation

A

hyperactivation: quick zig zags yield more power output from the tail, making the sperm more likey to interact with the oocyte

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12
Q

list the 6 steps in the sequence of events of fertilization

A
  1. sperm capacitation and hyperactive motility
  2. sperm BINDING to zona pellucida
  3. sperm acrosome react
  4. sperm get through zona pellucida
  5. sperm FUSE with oolema
  6. sperm enters oocyte
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13
Q

what 3 events occur once the sperm enters the oocyte in fertilization?

A
  1. resumption of meiosis II by oocyte
  2. sperm nucleus decondenses
  3. formation of two pronuclei (1M and 1F)
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14
Q

what determines how many zona pellucida proteins (ZP) exist and their function?

A

species variations

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15
Q

what is the general function of ZP 1 and ZP2?

A

maintain zona pellucida structure

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16
Q

what is the general function of ZP3?

A

sperm recognition of oocyte

17
Q

how is the function of ZP3 accomplished?

A

sperm have receptor for ZP3 on plasma membrane that can bind to ZP3

18
Q

what allows acrosome reaction of sperm?

A

binding to zona pellucida

19
Q

describe the acrosome reaction of sperm

A

plasma membrane and outer acrosomal membranes fuse, which forms holes that release acrosin and hyaluronidase, leaving sperm with only the nuclear membrane left

20
Q

at what angle in the hole in the zona pellucida left by the sperm and why?

A

an oblique angle to allow the zona pellucida to stay intact

21
Q

what is the perivitelline space (PVS)?

A

the space between the zona pellucida and the outside of the oocyte

22
Q

where do sperm enter before fusion with the oocyte?

A

the PVS

23
Q

list the 4 steps of sperm-oocyte fusion

A
  1. equitorial region settles onto microvilli on oocyte membrane
  2. fusion of sperm nuclear membrane and oolema
    3 and 4. oocyte engulfs sperm (tail and all) into cells, causing release of cortical granules to stop polyspermy
24
Q

how do cortical granules stop polyspermy?

A

by forming a chemical layer to stop sperm

25
Q

what initiates the calcium pulse?

A

PLCzeta from fertilization

26
Q

what is the role of the Ca2+ second messenger system in fertilization?

A

activates cell cycle for egg

27
Q

describe the zona bloack to polyspermy

A

loose cortical granules in ooplasm migrate to oolema, and form a chemical barrier/vitelline block

28
Q

how can you distinguish a male pronuclei?

A

it is usually smaller and may have a tail remnant

29
Q

what is syngamy?

A

fusion of male and female pronuclei, the moment of conception

30
Q

what is the fertilized oocyte called from syngamy until the first cell division and how long is it called that?

A

a zygote, about 18-24 hours

31
Q

when does a zygote become an embryo?

A

after the first cell division

32
Q

what is the approximate oocyte lifespan?

A

6-12 hours

33
Q

what is the approximate sperm lifespan?

A

24-48 hours after ejaculation