Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Endocrinology > fertilisation and contraception > Flashcards

fertilisation and contraception Flashcards

1
Q

what are the requirements for fertilisation?

A
  • sperm (that has matured and capacitated)
  • an egg (arrested at metaphase 1)
  • same place and same time
  • synchronised with receptive endometrium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what Is contained within ejaculate?

A
  • approx. 3ml
  • sperm + seminal plasma = semen
  • secreted by the accessory sex glands, seminal vesicles and prostate
  • roles in transport, nutrition, buffering and antioxidants
  • contains STIs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what does the bulbourethral gland?

A
  • pre-ejaculate
  • lubrication
  • neutralisation (pH) –> urethra transports urine too which is acidic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

why can’t sperm leaving the testis recognise the egg?

A

-need to undergo maturation in the male tract and capacitation in the female tract first

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is capacitation?

A
  • undergoes physiological changes
  • before capable of entering egg
  • flagellar beat is hyper activated
  • sperm gain ability to undergo acrosome reaction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what happens to sperm as they travel through the female tract?

A
  • numbers decrease rapidly
  • 200 million deposited In upper vagina –> 100,000 sperm enter uterus

1000 sperm enter each uterine tube -> 50% chance of choosing each uterine tube

  • high viscosity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

where does fertilisation occur?

A
  • in the ampulla region of uterine tube
  • sperm head for this region
  • egg doesn’t travel far
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how long do sperm and egg remain viable for?

A
  • sperm–> 5 days within female tract

- oocyte –> 24hrs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

list the steps of sperm interaction with oocyte vestments ?

A
  • remote detection of oocyte-cumulus complex –> chemotaxis may be involved?
  • penetration of cumulus cells outside egg
  • zona binding
  • acrosome reaction
  • zona pentatlon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the cumulus?

A
  • made of approx. 3000 cells embedded in a gelatinous matrix containing hyaluronic acid
  • closely apposed cells form a tight, organised layer
  • other less organised
  • sperm penetrate and can disperse the cumulus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

why is the zona pelludica important?

A
  • EC matrix surrounds all mammalian eggs (4 ZP proteins)
  • important for sperm-egg binding and induction of the AR
  • persists post-fertilisation
  • binding to the ZP induces the AR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

why is the AR so important?

A
  • vital
  • permits zona penetration
  • exposes the new inner membrane for oocyte fusion –> contains receptor crucial for activating the oocyte membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

why cant all sperm undergo the AR?

A
  • only capacitated sperm can that have hyper activated motility and have the ability to undergo the AR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what Is the process of fusion?

A
  • sperm penetrates the ZP and occupies the perevitelline spaceEquatorial segment of sperm head fuses with oocyte plasma membrane
    • Sperm nucleus is encased by a vesicle composed of internalised oocyte membrane
    • Large increase in the free [Ca2+]i – sweeps across egg from point of sperm fusion–> absolutely key for inducing next stages of development
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is Izumo?

A
  • sperm membrane receptors for fusion
  • only detectable on sperm surface after AR has occurred
  • KO of this protein abolishes fusion

its partner protein present on the oocyte PM is Juno

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what occurs during the oocyte activation process?

A
  • 1/3 mins–> large rise in I Ca which sweeps across the egg from point of sperm entry
  • followed by ca oscillations every 3-15 mins -> several hours –> important for triggering next stage
17
Q

what protein triggers oocyte activation via increased ca?

A
  • PLC zeta –> found in sperm only
18
Q

what mechanisms are in place to block polyspermy?

A
  • fast block –> electrical –> membrane depolarisation-> mins
  • slow block–> cortical reaction-> triggered by increase In [ca] 1 hr +
19
Q

what is the cortical reaction?

A
  • cortical granules contain mixtures of enzymes (proteases) which diffuse and fuse within the ZP following exocytosis from egg
  • induces the ZR
20
Q

what is the zona reaction ?

A
  • leads to an alteration in the structure of ZP catalysed by proteases form cortical granules
  • cleavage of ZP2 by ovastacin protease meaning sperm can no longer bind or penetrate the ZP layer
21
Q

what else prevents polyspermy?

A
  • loss of Izumi binding partner on egg- Juno
  • is shed from the oocyte PM with the cortical granules
  • is undetectable within 40 mins of fusion
  • no further sperm can fuse
22
Q

what does the sperm contribute to F?

A
  • haploid male genome
  • sex of baby determined
  • centrioles -> oocyte has none, this forming spindle for cell division
23
Q

what does the oocyte contribute to F?

A
  • haploid female genome
  • cytoplasm
  • all organelles
  • mitochondria (maternally inherited)
24
Q

what is the zygotic / pronucleate stage?

A
  • decondensation of sperm DNA (protamine and histone exchange)
  • male and female pronuclei replicate their DNA
  • pronuclei migrate towards one another
  • guided by sperm aster–>MT radiating from sperm centrosome
25
Q

what is syngamy? and what does it mark?

A
  • occurs at 18-24 hrs post F
  • pronuclear membranes break down
  • chromatin intermix
  • NE reforms around Z new nucleus
  • cleavage begins marking the end of F and the start of embryogenesis
26
Q

what are the cleavage stages?

A
  • zygote cleaves to form 2 blastomeres
  • 4 cell –> 8 cell stages–> morula (16-32)
  • ZP present
  • no cytoplasmic synthesis so each blastomere size decreases with each division
27
Q

what days does the blastocyst form?

A

late day 4/5

  • blastocoel cavity
  • distinct ICM and single layered trophoblast layer

2 poles formed (embryonic and abevbryonic poles)

28
Q

when does hatching occur?

A

late day 6 onwards

  • blastocysts expands out of hole in ZP-> at the abembryonic pole
  • implantation occurs
29
Q

outline the 3 key layers of the endometrium?

A
  • outer muscular myometrial layer (c)
  • inner uterine lining –> 2 layers
  • basalis stratum (B) + functional layer (A)
30
Q

what is the folicular phase ?

A
  • proliferative phase
  • post menstruation the endometrium is very thin and consists of a few layers of cells (basal)
  • first every 14 days of M cycle the endometrial cells proliferate in presence of oestrogen
31
Q

what is the luteal phase?

A
  • post ovulation
  • ovaries produce progesterone
  • known as the secretory phase
  • P stimulates synthesis of secretory material by glands rich in glycogen and gps/ AAs all providing nutrition for the blastocysts
  • this endometrium is now receptive and is ready for implantation of the blastocyst
32
Q

what is ovulation?

A
  • release of egg from ovaries

Endocrinology (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions