Brainscape's Knowledge GenomeTM

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


See full index

Theriogenology > Assisted Reproduction > Flashcards

Assisted Reproduction Flashcards

1
Q

What are the different methods of Assisted Reproductive Technology (ART)?

A
  • Artificial Insemination (AI)
  • Sex-selected (sex-sorted) semen
  • Embryo Transfer
  • In vitro fertilization (IVF)
  • Gamete Intra-fallopian transfer (GIFT)
  • Embryo-splitting
  • Cloning (Nuclear Transfer)
  • Cloning (Somatic cell nuclear transfer)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is Artificial insemination? what species is it used in?

A
  • Sperm is collected from the male and placed into the female reproductive tract to join with a naturally ovulated egg
  • Used In: bovine, equine, canine, ovine, other species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is sex-selected (sex-sorted) semen? What species is it used in?

A
  • Sperm is sorted by flow cytometry into predominantly X- bearing sperm and predominantly Y-bearing sperm aliquots. The sorted sperm is then used for AI
  • Used in: bovine & equine (also ovine, porcine, canine)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is Embryo transfer? What species is it used in?

A
  • AI or natrual service is used to inseminate a female. The resulting embryo(s) are collected prior to the time of “hatching” from the zona pellucida and transferred to a different female (recipient) for the rest of gestation
  • Used in: bovine & equine (also canine, ovine)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is In vitro fertilization (IVF)?

A
  • Fasting growing ART
  • A single sperm cell is inserted into an egg in a laboratory environment. Embryo is cultured on artificial media for several days and if the embryo proceeds to the blastocyst stage - it is transferred into a recipient (the donor or another female) for the rest of gestation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Gamete Intra-fallopian transfer (GIFT)?

A
  • Mostly experimental
  • An egg is aspirated from a donor female’s ovary prior to ovulation and then placed in the uterine tube of a recipient. the recipient is bread naturally or via AI
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Embryo-splitting? what species is it used in?

A
  • Identical twins (or more) can be produced by splitting a day-6 embryo (blastocyst before hatching from ZP) and placing the fragments into empty ZP shells and then transferring them into recipients (ET)
  • Used in: bovine and equine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Cloning (Nuclear Transfer)? What species is it used in?

A
  • Multiple genetically identical animals can be produced by taking cells from an embryonic blastocyst and implanting them into enucleated oocytes which are transferred to a recipient
  • Used in: Bovine, ovine, canine, and equine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Cloning (Somatic cell nuclear transfer)? what species is it used in?

A
  • Multiple genetically identical animals can be produced by taking adult cell and “re-programming” it to allow differentiation into an entire organism when implanted into enucleated eggs
  • Used In: ovine, canine, bovine, and equine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the advantages of Artificial Insemination (AI)?

A
  • Genetic improvement - widespread use of males likely to produce valuable offspring (based on the sire’s performance) or proven to have valuable offspring (based on many documented offspring)
  • Use males from anywhere in the world
    • few manageable health risks from movement of sperm and embryos vs. live animals
  • Don’t need as many males (safety and expense)
  • Removes/reduces risk of venereal disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the disadvantages of AI?

A
  • Skill needed for estrus detection
  • Trained inseminator - skill that must be hired or learned
  • Time and skill to commit to herd/animal reproduction
  • Increased cost per pregnancy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is Semen collected for AI? how do they work?

A
  • Artificial vagina:
    • males trained to mount a dummy/teaser animal
    • Stallions (temp/pressure ejaculator) - AV needs a jacket filled with warm water
    • Bull (pressure ejaculator) - does not need warm water jacket
  • Electroejaculation:
    • Specialized prove placed into the rectum applies a series of low-voltage pulses to the pelvic nerves involved in rection and ejaculation
    • for animal not trained to mount a dummy/teaser animal
  • Manual stimulation:
    • Pressure ejaculators - massage of penis
      • boars, dogs, whales, etc
    • Collection tube rather than true Artificial vagina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is Semen collected for AI? how do they work?

A
  • Artificial vagina:
    • males trained to mount a dummy/teaser animal
    • Stallions (temp/pressure ejaculator) - AV needs a jacket filled with warm water
    • Bull (pressure ejaculator) - does not need warm water jacket
  • Electroejaculation:
    • Specialized prove placed into the rectum applies a series of low-voltage pulses to the pelvic nerves involved in rection and ejaculation
    • for animal not trained to mount a dummy/teaser animal
  • Manual stimulation:
    • Pressure ejaculators - massage of penis
      • boars, dogs, whales, etc
    • Collection tube rather than true Artificial vagina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What supplies used in semen collection could be detrimental to sperm viability?

A
  • latex
  • plastic
  • lubricants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the requirements for sperm to be adequately fertile post-thaw?

A
  • Appropriate diluents / extenders
  • Appropriate sperm dilution (insemination dose)
  • Appropriate cooling and thawing speed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the appropriate diluents / extenders for Semen used for ART?

A
  • Non-penetrating cryoprotectant (e.g. egg yolk or milk product)
  • Penetrating cryoprotectant (e.g. glycerol, ethylene glycol, dimethyl sulfoxide) to protect from ice crystal formation
  • Buffer (e.g. Tris or Test) to prevent pH change
  • Sugar (glucose, lactose, trehalose) to provide an energy source
  • Salt (e.g. sodium citrate, citric acid) to provide proper osmolality
  • Antibiotic (e.g. penicillin, streptomycin) to kill pathogens
17
Q

What is the appropriate level of sperm dilution (insemination dose) for cryopreserved sperm

A
  • Bulls: 20 million sperm/dose
    • assume 50% live sperm post-thaw (I.e. 10 mil live sperm at insemination)
    • Can use a lot less (2 million sperm) - but must thaw and place semen VERY well (no room for error
18
Q

How is cryopreserved sperm appropriately cooled and thawed?

A
  • Rapid Cooling - in steps
    1. Add some extender ingredients and cool from 102F to 40F (refrigeration temp)
    2. Add cryoprotectants and packaging into 0.5 ml (or 0.25 ml)
    3. Freeze in liquid nitrogen vapor at -238F
    4. Store in liquid nitrogen until used at -320F
  • Relatively Rapid warming
    • Semen thawed at 95F for 12 seconds to one minute had best post-thaw viability
    • Semen thawed at 68F for 12 second to one minute had acceptable post-thaw viability
    • Semen thawed in 41F water bath or in a shirt pocket had lowest post-thaw viability
  • Once Thawed do NOT allow to cool (can get warmer)
  • Do NOT allow to go through thaw-cool cycles
19
Q

Is cryopreservation of sperm the same across species?

A
  • Sperm from different species are very different in size, shape, and lipid composition
    • These attributes all affect cryopreservation
    • Protocol that works for one will not necessarily work well in another species
20
Q

When does the bitch need to be inseminated when utilizing A.I? What if the semen is fresh? Chilled? Frozen?

A
  • Ovulation occurs 1 - 2 days after LH surge
  • Wait longer to breed after ovulation
  • Fresh semen:
    • Lives ~5-6 days in uterus
    • Breed 4-5 days after LH surge (3-5 days after ovulation)
  • Chilled semen:
    • Lives ~1-3 days after ejaculation
      • will lose at least 1 day in shipping
    • Breed 4-5 days after LH surge
      • If breeding 2x, do day 3 and 5; or 4 and 6 post LH peak
  • Frozen semen:
    • lives ~12hrs (max 24) in uterus
    • Breed 5-6 days after LH surge
    • Intrauterine insemination
      • surgical - laprotomy or laparoscopy
      • Transcervical catheterization
21
Q

When does a cow need to be inseminated when utilizing A.I?

A
  • almost always use frozen semen
    • fertility w/ frozen semen is equal to natural service
  • handle frozen straws carefully
  • Semen is placed in the uterus - pipette is passed through the cervix
  • Breed ~12hr after estrus first detected
    • Egg lifespan ~8-12hr
    • Sperm lifespan ~30-48hr
    • Ovulation occurs ~24hr after start of standing estrus (~10-14hr after estrus ends)
    • Need time for capacitation - so breed ~12hrs before ovulation
      • better “a little early” than “a little late”
22
Q

How is A.I. done in cattle?

A
  1. Sleeved arm placed in rectum
  2. Grab the cervix
  3. Introduce insemination gun through vulva/vagina
  4. Manipulate the cervix over the insemination gun
    • Cervical rings can make passing the gun challenging
23
Q

When does a mare need to be inseminated when utilizing A.I?

A
  • Fresh semen used immediately - does not have to be extended
    • Fresh semen used >10min after collections should be extended (pre-warmed)
      • Cold shock causes plasma membrane damage and acrosome changes - reduced fertility
  • Extended semen used w/in 6-12hr can be stored at room temp in dark, air-tight containter
  • Removing seminal plasma (centrifuge) delays capacitation - extends life of sperm for transport
  • To maintain viability for longer than 12hr - cool to 5-8C over a 2-3hr period
    • cool ~0.3C every minute
  • Ship in container designed to maintain steady temp
  • Do not expect chilled semen to remain viable longer than 60-72hrs
  • Inseminate mares w/in 24 hrs prior to ovulation
    • 1.8mg deslorelin acetate (GnRH agonist) can be used in mares with a >35mm follicle to induce ovulation
      • ~85% will ovulate w/in 24-48hrs
    • SucroMate Equine is a FDA-approved drug containing deslorelin - therefore use of compounded desloreline is illegal
24
Q

When does an ewe need to be inseminated when utilizing A.I? How are the inseminated via A.I.?

A
  • “Ram effect” to aid in synchronization
    • ewes must not be able to see/smell rams for at least 6wks prior to desired onset of cycling
    • Intro of rams will induce ovulation in ~3-4 days
  • AI not commonly done due to difficulty in detecting estrus
    • Also difficult to pass catheter through the cervix
  • Cervical AI - speculum used to visualize the cervical os and fresh or chilled semen is deposited in the cervix (not frozen semen)
  • Transcervical AI - Special forceps are used to pull the cervix into the vagina where another specialized scope is used to guide a catheter through the cervix
  • Laparoscopic AI = surgical endoscopic approach to deposit semen directly into uterus (can use frozen semen)
25
Q

What is Semen sexing?

A
  • In a normal ejaculate - ½ sperm cells contain X the other contain a Y chromosome
    • X chromosome sperm contain slightly more (~4%) DNA than Y sperm
  • Flow cytometry sorts X and Y sperm cells based on DNA content in the sperm head
    • results in ~90% accuracy of selecting X or Y sperm
  • No differences in offspring
26
Q

What are some problems with Semen Sexing

A
  • Sorting is slow - produce 6-10 straws per hour
    • Deep uterine insemination is used so that fewer sperm cells are needed per straw (2mill vs 15-30mill)
  • For many years, only fresh semen could be used
  • ¼cc straws are used for sex-selected semen (½cc for conventional semen)
    • More sensitive to cold shock and thawing errors
  • More expensive
  • Results in fewer pregnancies
    • sorting procedure causes decreased sperm viability and longevity
    • Acceptable success is likely only in high-fertility herds
  • Even with 90% success for sex-selected sperm due to random chance some herds will have less than 79% of calves with the desired sex
27
Q

What is Embryo Transfer (E.T.)?

A
  • Allows expanded use of genetically superior females
  • Superovulation = release of multiple eggs at a single estrus
    • multiple day injections of FSH at 12h intervals
  • Eggs from donor female can be placed into recipients either fresh or frozen
28
Q

How is Superovulation achieved in bovines

A
  • Donor female should be healthy and fertile
  • FSH injections are given every 12 hrs for 4 days during mid-diestrus
  • PGF2a is injected late in diestrus (4th day of FSH injections)
  • Can use ultrasound to determine how many ovulations
29
Q

How is the E.T. donor bred?

A
  • Breed with 2 straws every 12 hours (at 12, 24, and possibly 36 hrs after first detected in estrus)
  • Use semen proven to be firtile post-thaw
29
Q

How is the E.T. donor bred?

A
  • Breed with 2 straws every 12 hours (at 12, 24, and possibly 36 hrs after first detected in estrus)
  • Use semen proven to be firtile post-thaw
30
Q

How are the embryos for E.T. collected?

A
  • Collect about day-7 post estrus (bovine)
  • Collect 7 - 8 days after ovulation (equine)
  • Embryos have not ‘hatched’ from zona pellucida
  • Freezing equine embryos is not typically done - if planned embryos are collected on day 6
  • Given Epidural to prevent straining
    • Place a catheter through cervix - inflate cuff
    • Flush collection fluid into uterine horn
      • phosphate buffered saine (Dulbecco’s) + bovine serum
    • Drain fluid back out
    • Repeat in other horn with a new catheter (bovine)
    • Repeat 3x (equine
  • Collections fluid is filtered and examined under stereo microscope
  • High-quality embryos are collected for immediate (fresh) transfer or frozen for later transfer
31
Q

How is the embryo quality judged for E.T?

A
  • Normal shape (round) - 150-180 um
  • Compact blastomeres (vs. loosely packed)
  • Uniform blastomere size
  • No debris in cytoplasm
  • Smooth zona pellucida
  • Grades:
    • 1 - Excellent to Good
    • 2 - Fair
    • 3 - Poor
    • 4 - Dead or degenerating
  • Better success when transferring Grade 1&2
  • Grade 3 embryos can be transferred
  • ONLY Grade 1 embryos should be frozen
32
Q

What are the requirements for E.T. recipients?

A
  • Should be healthy and fertile
    • Don’t know how many embryos you will get, 6-8 is a good average
      • If transferring fresh - have 8 recipients ready
  • Should be synchronized so that they are on the same day of the estrous cycles as the doner (bovine)
  • Should have ovulated the day before or up to 3 days after donor (equine)

Theriogenology (29 decks)

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