Artificial Reproduction Technologies – Embryo Transfer Flashcards
What are the six steps involved in embryo transfer?
Selection, synchronisation, superovulation, insemination, recovery, transfer
What are the advantages of embryo transfer?
Maximises reproductive efficiency of high quality animals, speeds up the genetic improvement of a breed, circumvents infertility due to uterine/tract abnormalities, enables breeding from injured/aged females, enables athletic females to remain working, role in conservation of endangered species
What are the disadvantages of embryo transfer?
Expensive, potential narrowing of gene pool, enhancement of genetically linked undesirable traits by mistake, errors can occur at multiple stages
In an ideal scenario, what is the synchronisation between donor and recipient cycles?
The recipient is a few days behind the donor’s cycle, this gives a change for the embryo to settle and release MRP signal that prevents lysis of the CL
What method can be used to synchronise donor & recipient cycles?
Administer progesterone (mimics dioestrus), withdraw progesterone (mimics lysis of CL) & administer PGF2α (few days later in recipient females compared with donor female)
What is the purpose of superovulation?
Results in the stimulation and ovulation of multiple oocytes, common procedure in the cow, not possible in the horse
How is superovulation achieved in the cow?
D0 – first day of oestrus
D9-14 – administer gonadotrophins
48-72 hours later – administer prostaglandin, mid cycle CL regresses
40-56 hours later – in oestrus
What gonadotrophins can be used for superovulation in cattle?
Equine chorionic gonadotrophin, pregnant mare serum gonadotrophin, pituitary follicle stimulating hormone, human menopausal gonadotrophin
What is a potential limitation of superovulation in cows?
Ovarian response of an individual is highly variable, ranges from 0 to >30 ovulations
When is insemination carried out?
Before ovulation, semen is deposited in the uterine body or horn
Where does fertilisation occur?
Between the ampulla & isthmus
When is embryo collection carried out?
Embryo enters uterus on day 4 after oestrus, non-surgical flush of uterus via catheter on days 6, 7 or 8
What happens during embryo searching?
Embryos are located, graded and either transferred immediately to synchronised recipient or chilled or frozen
Where is the embryo transferred to?
Uterine horn on the same side as the CL, either surgically or non-surgically
What are the key points for a successful embryo transfer?
Quality recipients, quality embryos, cleanliness & gentle manipulation of the cervix
