Required Reading

Question 1

List the 4 steps that most occur before the embryo can attach to the uterus.

Answer 1

1. development w/in the confines of the zona pellucida
2. hatching of the blastocyst from the zona pellucida
3. materinal recognition of pregnancy
4. formation of the extraembryonic membranes

Question 2

A ______ is an organism in the early stages of developement.

Answer 2

embryo

Question 3

What is the term for a potential offspring that is still w/in the uterus, but is generally recognizable as a member of a given species?

Answer 3

Fetus

Question 4

What is the term for the product of conception?

Answer 4

Conceptus

Question 5

“Conceptus” includes what 3 things?

Answer 5

1. embryo during the early embryonic stage
2. embryo & extraembryonic membranes during the preimplantation stage
3. fetus & placenta during the post-attachement phase

Question 6

When does syngamy occur?

Answer 6

when the female & male pronuclei fuse

into a single diploid nucleus

Question 7

What is the term for the cells in a 2-celled embryo?

Answer 7

Blastomeres

AKA

Daughter cells

Question 8

What is the 8-celled embryonic stage called?

Answer 8

Morula

Question 9

What 3 components make up a Blastocyst?

Answer 9

• ICM (inner cell mass)
• Blastocoele
• Trophoblast

Question 10

What is the term used to describe the ability of a single cell to give rise to a complete, fully formed individual?

What embryonic stages exhibit this trait?

Answer 10

• Totipotent
• Blastomeres from the 2-, 4-, 8- & 16- cell embryos

Question 11

When does the morula reach the cow’s uterus?

Answer 11

4-7 days post ovulation

Question 12

When does the blastocyst reach the cow’s uterus?

Answer 12

7-12 days post ovulation

Question 13

When does the hatching reach the cow’s uterus?

Answer 13

9-11 d post ovulation

Question 14

Where does fertilization occur?

Answer 14

in the Ampulla of the Oviduct

Question 15

What 3 forces govern the hatching of the blastocyst?

Answer 15

1. growth & fluid accumulation w/in the blastocyst
2. production of enzymes by the trophoblastic cells
3. contraction of the blastocyst

Question 16

Which structure gives rise to the chorion?

Answer 16

trophoblastic cells

Question 17

When is the blastocyst totally dependent upon the uterine environment for survival?

Answer 17

after the zona pellucida ruptures

Question 18

List the 4 extraembryonic membranes

that make up the preattachment embryo.

Answer 18

• yolk sac
• chorion
• amnion
• allantois

Question 19

Which 3 embrynoic structures give rise to the

Amnion & Chorion?

Answer 19

• Trophoblast
• primitive endoderm
• primitive mesoderm

Question 20

Which structure gives rise to the yolk sac?

Answer 20

primitive endoderm

Question 21

Which embryonic structure makes up the Allantois?

Answer 21

the primitive gut

Question 22

What is the fetal contribution to the placenta?

Answer 22

the allantochorion

Question 23

What must occur to prevent luteolysis

& termination of pregnancy?

Answer 23

maternal recognition of pregnancy

Question 24

What does the blastocyst secrete to block the synthesis of uterine oxytocin receptors of the cow?

Answer 24

Interferons

(bIFN-t/bTP-1)

Question 25

What is the critical time period for maternal recognition of pregnancy by the cow?

Answer 25

13-14 days post ovulation

Question 26

What is the critical time of embryo attachement in the cow?

Answer 26

18-22 days post ovulation

Question 27

What is required for a successful pregnancy?

Answer 27

high blood [Progesterone]

Question 28

List some advantages of embryo transfer.

Answer 28

* circumvention of seasonal reproduction * enhanced generation of offspring in monotocous species * enhanced repro potential of endangered species * enhanced genetic diversity across a wide geographical region

Question 29

List some things involved in successful embryo transfer.

Answer 29

* synchronizing the cycles of donors & recipients * superovulation of the donor animal * AI of the donor female * recovery of embyros from the donor * maintenance of vialble embryos *in vitro* * transfer of embryos to recipient females

Question 30

What must occur in order for embryos from the donor animal to develop w/in the recipient animal?

Answer 30

the stage of their cycles must coincide

Question 31

What is usually used to achieve superovulation?

Answer 31

FSH | (gonadotrophins)

Question 32

How can you recover oocytes from the ovaries of a donor cow?

Answer 32

* surgically * using an U/S to aspirate follices * post-mortem in an abattoir

Question 33

List the 5 major steps of Embryo transfer in the cow.

Answer 33

1. sychronization of recipients w/ donor 2. Superovulation of donor 3. A.I of donor w/ semen from a superior bull 4. Recovery & I.D. of viable embryo 5. Transfer of viable embryo into synchronized recipients