Create
Learn
Share

Therio - Bovine - Pregnancy 1

rename
drraythe's version from 2017-09-25 20:59

Fertilization

Question Answer
Where does fertilization occur?Ampulla of the uterine tube
Where does Capacitation start? Where does it end?Begins in the uterine horn, & ends in the uterine tube
How does non-motile sperm get culled?They cannot get past the cervix
What is capacitation?Sperm have to undergo capacitation before they are capable of fertilization (it is the 1st step). It involves the destabilization of the acrosomal sperm head membrane allowing greater binding btwn sperm & oocyte → this is done by seminal plasma coatings being released along w/ some surface proteins. There is also Reorganization of surface receptors so that sperm can bind to zona pellucida (ZP)
Before fertilization can occur, Spermatozoa need to undergo what 3 things?In order:
(1) Capacitation
(2) Hypermotility
(3) Acrosome Rx
Why does frozen semen have such a short half-life?Frozen semen once thawed is already capacitated! This cuts down on the half-life
Where do sperm become hypermotile?In the uterine tube
When does the Acrosome Rx occur, & what happens during the Rx?Initiated by binding to the zona pellucida of the oocyte. Czs fusion of the spermatozoal plasma membrane & the outer acrosomal membrane (the outer plasma membrane of the sperm & the 1 below it which is the outer acrosomal membrane), which Exposes enzymatic vesicles (of acrosin hyaluronidase) which allow spermatozoon to tunnel (digest) through Zona pellucida
What happens after the sperm start to tunnel through the zona pellucida? (End w/ when a zygote forms)Fusion of oocyte & sperm plasma membranes, which then czs a Vitelline block & a Zona block (prevents polyspermy), & then sperm is engulfed into oocyte cytoplasm where there is fusion of male & female pronuclei to form a zygote
How is fertilization by more than 1 sperm prevented?Vitelline block & a Zona block (czd by fusion of oocyte & sperm plasma membranes)
How does the vitelline block work?Reduces the ability of the oocyte plasma membrane from fusing w/ additional spermatozoa
How does the zona block work?ZP undergoes biochemical change so that no other sperm can bind
What is superfecundation?The phenomenon whereby spermatozoa from multiple males can fertilize multiple oocytes (Can occur in dogs due to the sustained fertile period & multiple ovulations.)
What is a Zygote?Formed after fusion of male & female pronuclei
Embryo vs fetusEMBRYO: What zygote becomes after 1st division of cells up to D42 of gestation
FETUS: From D42 of gestation when embryo become more recognizable
What is Conceptus?The products of conception; often used interchangeably w/ embryo
memorize

Pregnancy

Question Answer
How does maternal recognition of pregnancy in the cow happen? (2 ways) when does it happen? Why is this important?(1) Secretion of IFN-τ (tau) by the conceptus
(2) Rapid outgrowth of the trophoblast to contact all parts of the endometrium. ← both of these occur by D15-16. This Prevents luteolysis & resumption of cyclicity to maintain the preg
*Duration of pregnancy in cattle?9mo (280 d)
How does the fetal gender affect duration of preg?Females cz a longer duration of preg than males
How does singles vs multiple fetii affect duration of preg?Singles take longer than multiples (mult take up more space-- get cramped sooner-- trigger preg sooner)
How does breed affect duration of preg?Bos indicus take longer than Bos taurus (possible size reason?)
How does nutrition affect duration of preg?Undernutrition = shorter gestation
What must you use to induce abortion during the 1st part of preg (up to D150) (must know what structure is involved in maintenance)ONLY 1° CL is maintaining preg, so you can just use Injxn of PGF2α
What must you use to induce abortion during the middle part of preg (D150-250) (must know what structure(s) is involved in maintenance)BOTH the 1° CL & the PLACENTA are maintaining preg, so you need to do PGF2α as well as Dexamethasone
What must you use to induce abortion during the last part of preg (D 250-280) (must know what structure is involved in maintenance)ONLY 1° CL is maintaining preg (placenta only does so from d150-250) so you can use PGF2α, OR Dexamethasone OR combination
What are 3 reasons you might want to treat misalliance or induce abortion during pregnancy?(1) Misalliance (eg. Neighbor’s bull got into your heifers…)
(2) Life threatening illness to dam (eg. Hydroallantois, pregnancy toxemia)
(3) Prolonged gestation
Induction of abortion >4 mos of gestation & induction of partus may result in what problems?RFM (retained fetal membranes) & metritis
What is the classification of distribution of chorionic villi of the placenta of cows?Cotyledonary (also, according to a diagram, the caruncular tissue invades into the chorionic tissue in cows
Vice versa in other animals)
What is the classification of Layers separating fetal & maternal blood of the placenta of the cow?Syndesmochorial (the epithelium of the maternal tissues is eroded to facilitate intercommunication) (sometimes classified as epitheliochorial bc the maternal layer is only partially eroded)
What is syndesmochorial?Epitheliochorial placenta where endometrial epithelium transiently erodes & regrows, exposing maternal capillaries to chorionic epithelium. Maternal capillaries are also exposed to binucleate giant cells in the trophoblast epithelium (fetal membranes) that secrete placental lactogen & pregnancy specific protein B
******SLIDE 32-- KNOW THIS PICTURE & BE ABLE TO LABEL IT (1) Amnion
(2) Allantois
(3) Chorion
(4) Yolk sac
(5) Caruncle
(6) Allantochorion
(7) Allantoamnion
(8) Amniochorion
(9) Umbilical cord
What’s the ChorionOuter layer in contact w/ maternal endometrium
What’s the Allantois?Space that is enclosed by the chorion, but outside of the amnion
What’s the Amnion?The innermost membrane that encloses the embryo
Why do you want to detect preg as early as possible, & what are 3 ways to do so?Do to avoid economic loss.
(1) Rectal palpation
(2) Ultrasonography
(3) Progesterone concentrations in milk/blood
Rectal palpation is the most commonly used way to detect preg. When is it most effective? (Most basic steps to it?)>95% accurate if >6wks (42 days) + experienced operator. (Locate the cervix, Retract the uterus into pelvis, gently palpate)
From rectal palpation, what are 4 definitive signs of preg?Membrane slip
Amniotic vesicle
Fetus present
Placentomes present
What's a Placentome?Maternal caruncle + fetal cotyledon
When do you do a membrane slip & what is it exactly?Btwn D30 & end of gestation. The whole thickness of the horn is carefully slipped btwn the index finger & thumb, feeling the allantochorionic membrane slip (false pos if uterine horn & broad ligament are grasped)
When do you palpate for the Amniotic vesicle? How do you do this?Palpable btwn D30 & D65, after that too soft & too large. The amniotic vesicle is gently surrounded by placing all 4 fingers dorsally & the thumb ventrally along the greater curvature of the horn. Egg shaped mobile structure that feels like a bar of Soap slipping through your hand
When do you determine preg by palpation & ballottement of the fetus?From D65 (~2mo to 4.5 mo), & then after 6mo - **Btwn 4.5 mo - 6 mo, the fetus CANNOT be felt; BUT feel the tension on the cervix, fremitus & placentomes
How do you perform a ballottement of the fetus?(Remember, from 2-4.5mo, then after 6mo) Put the palpating hand on the dorsal wall of the uterus & make a patting movement, the fetus is felt when it rebounds against the hand in response to that movement
When can you start to feel placentomes? How?Can be felt from D70 (2.5mo) & get larger w/ time- stroke flat hand over uterine surface the thickenings of the uterine wall can be felt
Well-developed CL is suggestive or definitive for preg? How would you describe this?SUGGESTIVE → a cow w/ a CL at 21d after breeding, a diestrous tone & no large follicle is most likely to be pregnant.
Where does the CL usually lie in relation to the preg horn?Ipsilateral - has to be on the same side to maintain the pregnancy on that side
If the cow is preg, & you palpate a follicle on the ovary, what do you think?Normal - FSH still secreted during preg (not suppressed by progesterone)
Is asymmetry of the uterine horns suggestive or definitive for preg? Why does this occur?SUGGESTIVE → due to accumulation of fluid in the pregnant horn, but not definitive bc can also be present in prepubertal cows or cows that recently aborted
If you palpate fluctuations of 1 or both uterine horns, what do you think this means?It is very suggestive of preg, starting at around D30 (1mo). The uterus is relaxed & thin walled due to progesterone, & the feeling is most apparent at the tip of the horn. (CAUTION: consider pyometra, mucometra, hydrometra, etc)
Explain Fremitus of the uterine artery → is this suggestive or definitive? What is it?Suggestive!
Characteristic type of vibration, which can be felt when the artery is slightly compressed btwn the thumb & a finger (Feels like sand grains rushing through the blood vessel)
*When can you feel fremitus of the uterine artery?3.5mo on the preg side. & then 5mo on the non-preg side (twins from 3.5m on both sides) (she skipped this slide, but, to find uterine aa: In the mesometrium in the lateral aspect of the cranial part of the pelvis, w/in a few cm of the external iliac artery. external iliac is fixed to the ilium, uterine artery is freely mobile)
What are 2 signs BEFORE D70 (2.5mo) of preg that are DEFINITIVE?(1) Pos membrane slip
(2) Presence of an amniotic vesicle
What are 2 signs AFTER d70 (2.5mo) of preg that are DEFINITIVE?(1) Palpate fetus or parts of it
(2) Feel placentomes
When can you feel membrane slip?30d (1mo)
When can you feel amniotic vesicle?D30-D65 (1mo-2.5mo)
When can you feel the fetus?D65-4.5 mos (2.5mo-4.5mo) (& then 6mo)
When can you feel the placentomes?D70 (2.5mo)
Explain in order from earliest sign to fetus, what you can palpate in the preg cowMembrane slip → amniotic vesicle → fetus (until 4.5mo) → placentomes → fremitus on preg side → fremitus on non-preg side → fetus (after 6mo & to term)
Early embryonal death is a risk factor w/ rectal palpation, esp if before day ___ or handled roughly. So after palpation you should recheck at ___(time)(1) Before d50 (1.5mo)
(2) 3-4m
What's pluriparous?Producing several young at a single birth.
Give some examples of stuff that can cz a false pos of pregPluriparous cow w/ a large uterus, cow 4,5-6m pregnant (this is false neg)
Cow in early puerperium (calved 2-3wks ago) or recently aborted
Cow w/ delayed uterine involution
Pyometra/mucometra
Distended urinary bladder
Gas filled colon loops or caecum
Firm masses like abscesses
Tumors
Bones of macerated fetuses or a mummified fetus
When can you Dx preg by Ultrasonography at the earliest? What do you see? (Universal for all sp!)From D25 → heartbeat visible
When can you see the heartbeat w/ ultrasonography? Placentomes? Ribs?Heart D25
Placentomes D33-38
Ribs D50-55
WHEN can you determine fetal sex via ultrasonography? HOW?Btwn D55-60 (after you can see ribs)
MALE the genital Tubercle moves towards the umbilicus
FEMALES the Tubercle moves towards the tail
If the genital tubercle moves towards the umbilicus, is it male or female?MALE (female is toward the tail)
When is [Progesterone] milk/serum looked at? Is this test better for determining if they’re preg or not preg?Performed on D21 after insemination (should have elevated [progesterone] if pregnant & basal [progesterone] if not pregnant). 100% accurate to confirm non-pregnant (high specificity), but 85% accurate to confirm pregnancy (lower sensitivity)
What are some reasons you might get a false pos P4 (milk or serum) test? (high progesterone but not preg)Samples taken at the wrong time (<d19 or >d21 after AI)
Poor management (AI at wrong time, or AI date recorded wrong)
Animal has had a shortened diestrous period (Endometritis)
Prolonged diestrous period due to retained CL
Luteal cysts
Pyometra
Endometritis
EED
What is Bovine Pregnancy Specific Protein B (bPSPB), & what can you use it for (when?)Protein secreted by the binucleate giant cells of the fetal trophoblastic epithelium... detectable around day 24
memorize