Exam 3 - Pregnancy & Gestation

Question 1

how does the placenta help the mother’s body not to attack the fetus as an antigen?

Answer 1

placentation allows for a compromise between the mother & fetus in a way that doesn’t compromise the dam

Question 2

what is the hemochorial placentation type?

Answer 2

mouse/humans placentas - direct communication between blastocyst & maternal circulation, so nutrients/hormones are released directly into the fetal bloodstream

Question 3

what is the epitheliochorial placentation type?

Answer 3

pig placentation type where the endometrium & chorion remain intact throughout gestation

nutrients must be transported through macromolecules

Question 4

what does anti-luteolytic mean?

Answer 4

prostaglandin E from the conceptus diverts & inhibits PGF2a

Question 5

what does luteotropic mean?

Answer 5

maintenance of a CL with a gonadotropin

Question 6

T/F: estrogen in the pig is both anti-luteolytic & luteotropic

Answer 6

true

Question 7

what is going on in ungulates with maternal recognition of pregnancy?

Answer 7

PGF2a from the uterine endometrium stimulates luteolysis, so removal of the uterus or damage to the endometrium will result in a prolonged CL

fetus must prevent luteolysis to survive!!!

Question 8

when does maternal recognition of pregnancy occur in pigs?

Answer 8

10-13 days post-estrus

Question 9

when does implantation happen in pigs? what is going on in the uterus at this time?

Answer 9

12-19 days post-estrus

pro-inflammatory period in the pig - initiates edema, increased vascular permeability in the endometrium, & this leads to increased communication between mother & conceptus

Question 10

how do pigs have the maternal recognition of pregnancy?

Answer 10

estrogen is released by the conceptus during 11-30 days into gestation & there must be 4 embryos total with 2 in each horn

injection of estrogen will initiate pseudopregnancy here

prostaglandin production in the endometrium is shifted from PGF2a to PGE2 - uterus & conceptus produce PGE2!!!!!!

maternal recognition happens

Question 11

what is sensitivity & specificity in relation to pregnancy diagnosis in food animal species?

Answer 11

sensitivity - ability to detect pregnant animals correctly

specificity - ability to detect non-pregnant animals correctly

Question 12

T/F: in early gestation of mares, the conceptus doesn’t elongate

Answer 12

true

Question 13

what is the average length of gestation in sheep? how long is it dependent on the corpus luteum?

Answer 13

140-155 days

5-60 days dependent on the CL

Question 14

what happens if a sheep is exposed to veratrum californicum on day 14 of gestation?

Answer 14

prolonged gestation, hypoplastic pituitary glands, & hypoplastic adrenal glands, & can see cyclops in babies

Question 15

what diagnostic is commonly used to diagnose pregnancy in sheep?

Answer 15

intra-rectal/transabdominal ultrasound

can do this at 40 days gestation - also detects fetal numbers well

Question 16

what is a way to figure out that a lady sheep is not pregnant?

Answer 16

she returns to estrus lol

Question 17

T/F: abdominal ballotment performed on days 90-130 is poorly accurate for diagnosing pregnancy in sheep

Answer 17

true

Question 18

how long is gestation in pigs? how long is it CL dependent?

Answer 18

114 days - 3 months 3 weeks 3 days

CL dependent throughout the pregnancy

Question 19

how many embryos must a pig have to maintain pregnancy?

Answer 19

4 - 100% fertilization rate but 20-30% of embryos die in the first 30 days

Question 20

in sow pregnancies, the ____ migrates to the uterus at day ___ & secretes _______ at days 10-11

Answer 20

embryos

estradiol

Question 21

what are some reasons that estrus detection in sows may give you false positives when trying to diagnose pregnancy? what about false negatives?

Answer 21

the pigs can be in anestrus or they could be submissive sows

group of pigs too big or insufficient management of sows

Question 22

what are the advantages of using PGF2a levels in sows to determine pregnancy? what are the disadvantages?

Answer 22

it is very sensitive & 70% specific - PGF2a levels are secreted at days 12-15 in non-pregnant sows!!!!

impractical to do this

Question 23

how is estrone sulfate used to detect pregnancy in sows? what are the disadvantages of it?

Answer 23

sensitive/specific test that is done between days 25-30

not commercially available for swine

Question 24

T/F: in sows, early pregnancy factor B is produced only in the ovaries during pregnancy

Answer 24

true

Question 25

what is the average length of gestation in cows? what is it influenced by?

Answer 25

273-296 days - influenced by breed

Question 26

what is considered to be premature gestation in cattle?

Answer 26

premature if before 250 days - calf unlikely to survive

Question 27

what cows commonly deal with prolonged gestation lengths?

Answer 27

large fetuses & bull calves

Question 28

what are the 4 positive signs of pregnancy in cattle?

Answer 28

1. amniotic vesicle at days 30-65 2. fetal membrane slip at 35 days-term 3. fetus at 65 days 4. placentomes present at 75 days, easily palpated by 85-90 days

Question 29

what are some secondary signs of pregnancy in cattle?

Answer 29

fremitus in the middle uterine artery - but not diagnostic milk/blood progesterone levels (low at days 2-24 after breeding) - 98% diagnostic for non-pregnant cows

Question 30

when can transrectal ultrasound be used in cattle for detecting pregnancy? what about for fetal sexing?

Answer 30

20-25 days after breeding fetal sexing at days 55-75

Question 31

what is the average length of gestation in horses? when does the embryo make it to the uterus?

Answer 31

340 days average trans-uterine migration - embryo in the uterus 6.5 days after ovulation

Question 32

what do we call premature births in horse pregnancies?

Answer 32

fetus delivered before 320 days

Question 33

why may a horse have a prolonged gestation? what is the exception to this?

Answer 33

small fetus - exception is fescue toxicity

Question 34

how is pregnancy diagnosed in horses?

Answer 34

transrectal ultrasound done 14 days after ovulation

Question 35

what is the only primary sign of pregnancy in the horse?

Answer 35

ballotment of the fetus

Question 36

when is sexing of the fetus done in horses?

Answer 36

days 55-75 with a transrectal ultrasound

Question 37

in an ewe, what happens if they lose their CL before 55 days of gestation? what about after? why is this important?

Answer 37

<55 days - abortion > 55 days - maintained pregnancy ewes need their CL up to day 55 because it is what is producing progesterone up until that point!!!

Question 38

in an cow, what happens if they lose their CL before 200 days of gestation? what about after? why is this important?

Answer 38

<200 days - abortion > 200 days - maintain pregnancy the CL of the cow produces progesterone throughout their pregnancy, but by day 200, the placenta is also producing progesterone & this maintains the pregnancy at 6-8 months

Question 39

how is the pregnancy maintained in the mare throughout gestation?

Answer 39

primary CL produces progesterone until day 35-40 & then secondary CLs form due to eCG release from endometrial cups both CLs regress around 150 days of pregnancy placenta starts producing progesterone around 120 days gestation

Question 40

T/F: the ovaries of a mare can be removed around days 90-120 & the pregnancy will still be maintained

Answer 40

true

Question 41

the ____ & ____ both have a corpus luteum producing progesterone throughout pregnancy

Answer 41

sow & doe

Question 42

T/F: asynchrony between the mother & embryo is what causes early embryonic death

Answer 42

true

Question 43

T/F: litter bearing species have uterine space limitations

Answer 43

true

Question 44

why do late developing embryos die off?

Answer 44

they fail to provide the proper signal to the mother that they are there

Question 45

what is the pathogenesis of early embryonic death?

Answer 45

late onset of the 1st meiotic division so oocyte maturation is late (pig ovulation occurs over several hours, so there is a delay in ovulation) late developing embryos fail to provide a proper signal to the mother for pregnancy recognition

Question 46

what hormone is vital in cows & sheep for pregnancy recognition? why?

Answer 46

interferon tau - suppresses the endometrial levels of PGF2a

Question 47

when does the conceptus elongate in cow & sheep pregnancy?

Answer 47

cows - days 14-16 sheep - days 12-13

Question 48

what is the process of maternal recognition of pregnancy in mares?

Answer 48

conceptus doesn't elongate in early pregnancy only the embryo reaches the uterus due to the secretion of PGE2 by the conceptus - NO FERTILIZED OOCYTES in the uterus!!!!!! PGE2 causes relaxation of the isthmic smooth muscle to release the embryo embryo must be able to migrate throughout the uterus to prevent PGF2a release - critical period is 12-14 days post-ovulation!!! estrogen & interferon are not anti-luteolytic they are the ungulates that produce chorionic gonadotropin due to endometrial cup formation which provides maintenance of the secondary corpus luteums the blastocyst capsule, mucin-like proteins, secrete from the trophectoderm after the blastocyst enters the uterus zona pellucida is then shed after the capsule formation - capsule is elastic & protects the embryo while it migrates throughout the uterus

Question 49

what is the process of maternal recognition of pregnancy in humans & mice?

Answer 49

the embryo attaches to the endometrium & invades (hemochorial) & there is a direct communication between the blastocyst & maternal circulation nutrients & hormones are released directly into the fetal bloodstream

Question 50

what is the process of maternal recognition of pregnancy in pigs?

Answer 50

the endometrium & chorion stay intact throughout the pregnancy (epitheliochorial) nutrients (iron) must be transported through macromolecules

Question 51

what are the two types of hormone groups that are involved in maintenance of the corpus lutuem as a component of maternal recognition of pregnancy?

Answer 51

anti-luteolytic - PGE2 from the conceptus which diverts PGF2a & inhibits it luteotropic - maintenance of CL (gonadotropin) in pigs - estrogen does both!

Question 52

what is the process of maintenance of the corpus luteum in human pregnancies?

Answer 52

luteolysis is initiated by the ovary trophoblast cells produce chorionic gonadotropin that binds to LH receptors & produce progesterone & protects against PGF2a

Question 53

what is the process of maternal recognition of pregnancy in ungulates?

Answer 53

PGF2a from the endometrium is the stimulus for luteolysis - removal of the uterus or damage to the endometrium will result in a prolonged CL conceptus, to survive - must prevent luteolysis

Question 54

what are secondary signs of pregnancy in a mare diagnosed by manual rectal exam?

Answer 54

size of the bulge in the uterus tone of the cervix & uterus

Question 55

why is fremitus in the middle uterine artery not a for sure sign that a cow is pregnant?

Answer 55

it occurs when the uterus is large - postpartum or pyometra! not specific for pregnancy!