ART2: embryo transfer, stem cells and cloning

Question 1

what are stem cells

Answer 1

unspecialised cells with capacity to self renew for long periods
self renewal = ability of stem cells to divide and maintain an indifferentiated state

Question 2

what is totipotent

Answer 2

able to form entire organism

Question 3

what is pluripotent

Answer 3

able to form all the body’s cell lineages, including germ cells

Question 4

what is multipotent

Answer 4

can form multiple lineages that constitue an entire tissue or tissues

Question 5

how are stem cells used in medicine

Answer 5

• cell based therapies (tx where stem cells form cell types that are damaged)
• drug development and screening
• disease models
• study of early development

Question 6

list key artificial reproductive techniques

Answer 6

• superovulation (stimulation of more dominant follicles to form that would normally occur)
• ovum pick up (collection of oocytes from multiple follicles in vivo)
• in vitro fertilisation (fertilisation of the oocyte with sperm in a petri dish)
• emrbyo transfer (transfer of an embryo, derived from the mating of valuable parents into a fertile but less valuabel recipient female who carries the pregnancy to term and offspring to weaning)

Question 7

what are the advantages and disadvantages of embryo transfer

Answer 7

Question 8

outline the timeline of the embryo transfer procedure

Answer 8

step 1: give gonadotrophin tx from day 9-14 of oestrus (ECG or purified FSH)
48-72 hours later administer pgf2a to lyse CL
40-56 h later cow is in oestrus
inseminate at least twice 12-18 h apart
step 2: inseminate before ovulation (semen deposited into uterine body or horn)
step 3: enters d4 post ovulation as morula/early blastocyst. non-surgical transcervical flush of uterus via catheter on day 6,7 or 8. flush medium is filtered to collect embryo and transferred to recipient to continue to grow and implant
step 4: grad embryos collected and transfer immeditaely to synched recip or chilled or frozen
step 5 and 6: embryo transfer = oestrus cycle closely synchronised to within 24 hours behind donor
transfer to uterine horn ipsilateral to CL via surgican or non-surgical transfer (must be clean, via cervix via fine pipette or catheter)
70% preg rate achievable

Question 9

is superovulation possible in the cow and horse

Answer 9

common procedure in the cow (respond well to FSH treatment)
not possible in horses