Exam 2: Fertilization/ Implantation Flashcards

1
Q

sperm structure

A

head
mid piece
tail

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2
Q

sperm head

A
  • haploid
  • nuc with highly condensed chromatin wrapped around protamines
  • protamines= specialized basic histone
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3
Q

sperm acrosome

A
  • ant 1/2 or 1/3 of sperm head
  • thin, double layered membrane sac
  • hydrolytic enzymes critical for fertilization
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4
Q

sperm tail

A
  • 9+2 axoneme microtubule structure
  • distributed on either side for movement, gives tail pattern

**kartagener’s= defective cilia, immotile sperm

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5
Q

normal semen analysis values

A

vol >1.5ml
concentrations > 15x10^6/ml
motility > 32%
morphology 4%

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6
Q

female fertility eval

A

to test how many eggs are available: US, blood draw for FSH, E2, AMH
***cannot do with someone on birth control

euploid embryos decrease with maternal age

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7
Q

when does woman have peak # of oocytes?

A

20 weeks gestation

exponential decay after that

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8
Q

primary oocytes are arrested at _______

A

prophase I –> after LH surge, become secondary oocyte + 1 polar body

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9
Q

Zona pellucida

A
  • shell like structure that surrounds oocytes
  • glycoprotein sheet made up of protein, hexose, sialic acid, sulfate
  • GPs: Z1, Z2, Z3
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10
Q

T/F: mutated or inactivated zone proteins is a cause of infertility?

A

True. They act as the “sperm receptors”.

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11
Q

quick, run through the steps of sperm-oocyte fusion

A

1) ovulation, collection of oocyte
2) deposition of sufficient # sperm
3) sperm capacitation
4) sperm traverse cumulus oophorus
5) sperm meet ZP
6) acrosomal rxn
7) plasma mem fusion
8) oocyte activation/ cortical reaction
9) male pronuclei formation

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12
Q

sperm capacitation

A
  • “activation” to be able to undergo acrosomal rxn
  • acq ability to capacitate in distal genital tract of male
  • req Ca, ATP, etc
  • capacitated sperm display HYPERMOTILITY—–> go and bind the egg
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13
Q

where on the oocyte do capacitated sperm bind?

A

Z3 on zona

“sperm receptor”

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14
Q

acrosomal reaction

A

outer mem of acrosome region fuses with plasma mem of sperm

fusion of membranes –> release hyaluronidase and acrosin –> complete fusion of sperm with oocyte

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15
Q

whats the protein that facilitates fusion of sperm and egg?

A

fertilin

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16
Q

cortical reaction

A

occurs as soon as first sperm fuses

  • release cortical granules
  • changes ZP3, which makes oocyte impenetrable
  • prevents polyspermy
17
Q

male pronuclei formation

A
  • protamine unwinds –> SS bond reduced by oocyte glutathione
  • sperm nuclei decondense
  • form male/female pronuclei!
18
Q

day 4 embryo

A

morula

-it is a morula usu by the time it reaches uterus

19
Q

day 5 embroy

A

blastocyst

  • trophoectoderm –> becomes placenta
  • inner cell mass –> becomes fetus
20
Q

implantation timeline

A
  • 6-7 days after conception

- req interaction of trophectoderm and primed lining of uterine cavity

21
Q

where does implantation most commonly occur?

A

posterior wall, midsagittal plane

but it can implant anywhere

22
Q

blastocyst hatching

A
  • blasto “escapes” from ZP (day 6-7)

- unfertilized eggs do NOT hatch

23
Q

can you have implantation without hatching?

A

NO.

24
Q

decidualization

A
  • morphological and biochemical differentiation of uterine stromal cells
  • critical for:
    1) trophoblast invasion
    2) placental formation
25
Q

decidualization is dependent on what signals?

A

progesterone, estrogen, cAMP

26
Q

what does decidualization start?

A

day 23 of cycle

-if implantation occurs, process expands to remaining stromal cells

27
Q

what is the window of implantation?

A

SMALL (days 20-24)

  • when epithelium lining of utereus is ready to accept
  • dependent on progesterone being secreted from corpus luteum
28
Q

what are the 3 stages of implantation?

A

apposition - loose, unstable connection of trophoectoderm/endo lining

adhesion- integrins, L selectin, hep sulfate proteoglycans

invasion - buries into endometrium

29
Q

placenta previa

A

implantation occurs near cervix

  • can be obstructing –> Csection
  • vascular–> causes bleeding
30
Q

placenta accreta

A

implantation at site of prior uterine scar

  • can be traumatic birth
  • can req hysterectomy at birth
31
Q

medical treatment of ectopic pregnancy

A

methotrexate –> chemotherapy drug that targets rapidly dividing cells

32
Q

surgical treatment of ectopic pregnancy

A

if too big for drugs

  • salpingectomy –> removal of FT (usu preferred)
  • salpingostomy –> surgical unblocking of FT