Anatomy Of Pregnancy 2: Anatomical features of pregnancy in the sow, mare, ruminant and carnivores Flashcards
Which species are of only litter bearing?
Carnivores, rodents & pigs
What shape are the blastocysts in the sow initially? (Post fertilisation)
Spherical
Describe the movement of the blastocysts post fertilisation in uterus in the sow and all that occurs at the same time
-Spherical Blastocysts come into uterine horn from uterine tube/oviduct
-remain mobile at initial stage and disperses along uterine horn due to peristaltic movement
-as blasocysts expand and start growing, become elongated- long thin tubes
-allows surface of whole of blastocyst to make contact with endometrium
-this initiates arterial recognition; preventing release of prostaglandin
What does the peristaltic movement of the sow blastocyst in uterine horn allow
Allow blastocysts to evenly distribute themselves across both uterine horns
How long are the blastocyst tubes in the sow after changing shape from speherical to elongated?
1m each
In what occasion would maternal recognition not take place in a sow? what does this mean for pregnancy?
If there are less than 3 conceptuses (embryos)- this means pregnancy is terminated as release of prostaglandin will not be prevented. (If there is not enough blastocyst covering endometrium surface area, body doesn’t recognise the pregnancy as “worth it”)
What types of placenta are found in the sow?
1.Diffuse;
-placental zone- with villi
-paraplacnetal zone- no villi (the edges of placenta)
2.Epithelial-chorial;
-no invasion of endometrium i.e will have 6 layers to pass through for exchange of nutritional material
3.Non-deciduate;
This means no loss of maternal tissue meaning afterbirth placenta shed cleanly with no loss of maternal tissue
What is avascular extremity of placenta
Occurs in what kind of animals
2 embryos neighbouring the avascular extremities of one placenta link up and fuse together
-occurs in litter bearing animals
Survival of piglet embryos depends on…
What do the embryos do in the uterus?
Survival depends on nutrition which is directly correlated with surface area of endometrium being covered by the embryos
-embryos compete for nutritional support; as they grow each embryo tries to take up a such space as they can which means there’s only so many pregnancies that sow can support
-this means surplus embryos die & reabsorbed at early stage of development
Blastocyst in the mare
-enters uterus when
-remains what shape
-protected by what?
-initially very…
-approx 6 days
-remains spherical protected by a protective capsule called embryonic vesicle
Initially very mobile; covers the full length of the uterus by movement of uterine contractions
Describe what happens to the blastocyst in the mare post fertilisation
—Embryonic vesicle covering blastocyst enlarges
-at day 16 enlarges to the point of it being unable to pass through body horn junction
—at day 30 becomes palpable
—day 28-33 continues to ^ in size
-allantois begins enlarage whilst yolk sac regresses
-embryo begins to move dorsally in vesicle
—at day 40
• Chorio-allantois engulfs yolk sac
• Umbilical cord forms
• Contains remnant of yolk sac
• Foetus moves ventrally as it elongates
—at day 60-100
• Foetus too deep in abdomen to identify
What type of placenta is found in the mare?
Diffuse, epitheliochorial, non-deciduate placenta
Placenta in mare is fully formed around what day?
Day 140
What are the microcotyldeons
What species are they found in
Microscopic microvillous tufts present only during pregnancy- help increase S.A to improve transfer of material between foetal and maternal circulation
Found in mare
How long after birth should the mare shed the placenta? What if it doesn’t in this time period?
<6 hours after
Can be life-threatening if doesn’t- mare can develop infections if it doesn’t shed it in time
What are hippomanes
Soft lobs of material- accumulations of waste product of the Allantois that are sometimes shed after birth- of no concern
Found in mare
Describe the action/process of blastocyst in the cow
-Morula enters uterus approx day 4
-Becomes blastocyst approx day 8
-blastocyst elongates significantly; occupies most of uterine horn; means not very mobile. Elongation however still allows good cover of S.A and exchange of nutrients
-starts off at side of corpus luteum but then blastocyst expands to other side as well (when looking for pregnancy in cow, will be initially looking at same side as CL)
Name the type of placenta found in the cow
Cotyledonary, epithelio-chorial, non-deciduate placenta
Cotyledonary-> patches of villi found around the placenta. Develop on surface of chrorion
What is the placentome (found in cow)
Linking of the cotyledon of foetal side to the caruncle of maternal side
Around what day can you identify a pregnancy in the cow?
Using what?
Day 21
Using rectal US
What can you start seeing on ultrasound in a cow/other species when looking for pregnancy
-Can start seeing heartbeat of embryo
-corpus luteum
-fluid filled structure in the uterus
What type of placenta is found in the ewe
Cotyledonary, epithelio-chorial, non-deciduate placenta
In ewe there is much higher incidence of ______ than in other species
Twins
What is transuterine migration?
When an embryo moves from one uterine horn (containing the CL) to the other uterine horn
What is freemartinism
-which animal is it most common in
Occurs in females carrying one female and male embryo twins. The placental blood vessels of the twins link. This fusion results in the transfer of male hormones to the female fetus, which can lead to various developmental abnormalities of the reproductive tract and the female’s inability to reproduce.
-cow
Is freemartinism a problem in ewes?
Nope
Techniques used to detect pregnancy in ewe
-Abdominal ballotment- feeling the foetus through the abdominal wall (towards end of pregnancy)
-US; 70-105 days into pregnancy
What shape are the caruncles in the sheep?
Doughnut shaped
Describe action of the embryo post fertilisation in the bitch relative to days of pregnancy
-Embryonic vesicles mobile till day 13, this mobility allows for even distribution of embryos across both uterine horns
-no need for maternal recognition of pregnancy
-by day 16 pregnancy can be identified using transabdominal ultrasound; Series of anechoic (black) spherical vesicles seen
-at day 21 embryo is visible plus a heartbeat
-at this stage chorio-vitelline (yolk sac) is functional/present
-at day 24; Chorio-allantois is complete, Yolk sac regresses but persists to term as remnant in umbilical cord (remnant is thought to have a haematopoeitic function
At what day is the pregnancy detection used in a bitch
After 28 days post mating
What ways is a pregnancy in the bitch detected?
US examination
Palpating at day 21-31
(US examination more reliable)
What type of placenta is found in the bitch?
Zonary, endothelio-chorial, deciduate placenta
Zonary;
-Most of chorion has no villi; only a little found at paraplacental area
- villi most;y located. In zonary band; Encircles central region of chorionic sac
Villi invade endometrial glands:
Destroy glands, maternal epithelium and connective tissue
(Only contains 4 cell layers in between foetus and placenta)
What is marginal haematomas?
What can this cause during parturition (birth)- what are these called
Areas where blood has collected due to destruction of blood vessels. Marginal means it has specifically developed along the periphery of a specific tissue.
-bitch might expel discoloured fetal fluids due to breakdown of blood products-it is normal
-breakdown products released at called uteroverdin
Whereabouts does marginal haematomas occur in a butchers uterus?
Along periphery of the zonary band
What are some reasons/applications of US in the bitch
• Pregnancy detection
• Counting foetuses!-easier to count in early pregnancy as they are clear to see
• Foetalviability
• Gestational age/ date of whelping
At what day is foetal anatomy in a bitch identifiable on an US
Day 35
Around what time can radiographies be used for pregnancy detection in bitches
After day 42
What is a radiography used for in pregnancy detections in a bitch?
Foetal numbers-count skulls
Difficult to assess viability/gestational age
What colour is uteroverdin in the dog and cat
Dog- green
Cat- brown
When a pup/kitten is pushed out the womb, it is delivered in the __________.
Amnion
What is INF
Interferon- a type of protein that is produced by the body’s immune system in response to a viral or bacterial infection
Describe what is happening on this immunology graph
On anki
What is passive immunity
-what does it do
Immunity that is passed on when baby animals ingest colostrum
1. New born animal gains immune response- may become immune from antibodies made by mother (these antibodies that the newborn now has at however not made by the new born but by the mother, so will diminish in time)
Passively-acquired immunity can interfere with what?
Vaccination
What antibody comes first in the
-primary
-secondary
response, IgG or IgM
Primary; IgM then IgG
Secondary; IgG first and a little bit of IgM later
What is colostrum
Milk of new born mammals-
Source of nutrition full of vits, growth factors & immunoglobulins
Also a source of passive immunity
In animals which antibody is primarily found in colostrum?
IgG
Why are the immunoglobulins levels in colostrum/milk different between animals and humans?
Due to differences in their placentas; the thicker the barrier between the maternal and foetus, the less immunoglobulins can pass through
-animals have a much thicker barrier between maternal and foetus and therefore immunoglobulins from milk are not enough to sustain the animal, so they need colostrum
What are the 4 different types of antibody transfer in placentation
Haemochorial
Endotheliochorial
Syndesmochorial
Epitheliochorial
Haemochorial
-which animals have this type of placentation
-what is it
-Rodents, primates
-maternal and foetal cell layers/barrier is very thin
-immunoglobulins can be actively transported to foetus
Endotheliochorial
-cats & dogs
-get limited IgG transferred to foetus through barrier
Syndesmochorial
Ruminants
No trans-placental transfer of IgG
Epitheliochorial
-in horses and pigs
-no trans-placental transfer of IgG
Why can passively acquired immunity interfere with vaccinations
presence of pre-existing antibodies can neutralize the vaccine antigens, thereby preventing the new born from mounting an effective immune response
What is the immunity gap in a newborn animal
When new born is no longer gaining immunity from maternal antibodies, however vaccination with still be interfered/impeded
What is a way around passive immunity interfering with vaccines
Immunising the mother of the new born with a vaccine, which then allows passive immunoglobulins to be passed on to the new born and be protected from infections caused early on in birth
How do we prevent passive immunity interfering with vaccines in puppies
Vaccinated twice; once at 8 weeks and once at 12
What do virus neutralising antibodies actually do?
Coating of virus with antibody Prevents subsequent stages in the viral life-cycle post-infection- stops replication
-blocks interaction between virus and receptor
-opsonisation encourages phagocytosis of virus via Fc receptors & complemnt receptors
How to viruses escape neutralisation of antibody
Sometimes can develop a mutation during replication in the viral genome which results in antigenicity of viral proteins; antibody no longer recognises virus
Which virus commonly undergoes antigenic drift and antigenic shift?
Influenza virus
What is antigenic drift
process by which viruses accumulate mutations in their genes over time that result in changes to the surface proteins of the virus. This means the antibody may not be able to recognise the virus anymore; immunity has been evaded
What is antigenic shift
process by which influenza viruses undergo a major and abrupt change in their genetic makeup, resulting in the emergence of new strains that are fundamentally different from the previous strains. This can occur when two different influenza viruses infect the same host cell and exchange genetic material, resulting in the creation of a hybrid virus that has a novel combination of surface proteins that the immune system has not previously encountered.
Name the 2 surface proteins of the influenza virus
neuraminadase (NA)
haemagglutinin (HA)
A successful vaccine should…
-induce both cellular and humoral immunity
-elicit the production of high affinity antibodies
Vaccines are grown in…
Eggs (like real eggs)
~900 million hen’s eggs are required to make ~300 million doses of influenza vaccine (US.DHHS)
What is the only virus which a retroviral vaccine works on?
• Feline leukaemia virus gp70 antigen
What do the interferons do to “buy time” for the immune response?
Act on neighbouring uninfected cells and tell them to stop growing virus; signal to other cells to activate their antiviral defence;
-switch off protein production/ inhibition of protein synthesis
-degradation of viral RNA
-prevent release of viral particles
All leads to inhibition of viral spread
What else can interferons do?
Inducing/switching on intrinsic antiviral factors;
APOBECs
TRIMs
Tetherin
