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BVMS Module 5 > Week 2 > Flashcards

Week 2 Flashcards

1
Q

describe fertilisation?

A

Fertilisation = pre natal phase, emybro change: becoming multicellular and gastrulation
Two haploid gametes fuse to form a new diploid zygote

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2
Q

how is sperm used in fertilisation?

A

must reach ampulla to be capacitated, allows intretaiotn with egg via, ZP3 protein

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3
Q

what happens when sperm reaches the egg?

A

1st spermatozoon enters the egg, calcium wave in cytoplasm occur
Egg undergoes cortical granule reaction.
Exocytosis of granules causes hardening of Zone Pellucida (ZP)
meiosis II occurs and completes the 2nd meiotic division with

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4
Q

what is the zona pellucida?

A

the thick transparent membrane surrounding a mammalian ovum before implantation.
communication between oocytes and follicle cells during oogenesis; protects oocytes, eggs, and embryos during development, and regulates interactions between ovulated eggs and free-swimming sperm during and following fertilization.

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5
Q

what is emybroic cleavage?

A

single fertilized cell into multicellular complex within the ZP.
Zygote undergoes mietoic divisions and cel formed called Blastomeres (totipotent)
constant dividing into 16 blastomeres stage = morula
enters uterine horn in most species
cell differentiation - 64 blastomeres stage

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6
Q

what occurs after emybroic cleavage?

A

oocyte passes onto mitochondria, mRNA + proteins for initial emybro cleavage.
Activation of emybrionic genome must occur in 3rd cleavage - cell arrest can occur here.

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7
Q

what are Morula Blastomeres?

A

compaction occurs - tight complexes are made - cells lose totipotency,
morula uses uterine fluid until central fluid filled cavity = blastocyte

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8
Q

how can morula blastocytes be used for clinical application?

A

emybro sexing
prenatal diagnoses of genetic disease
emybro transfer in cattle
emybrioic stem cells - pluripotent cells

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9
Q

what about monozygotic twins?

A

arise from a single egg which was fertile by a single spermatozoon,

1) split at the 2nd blastomere stage
2) duplication of inner cell mass with blastocyst
3) formation of 2 primitive streaks

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10
Q

what must the blastocysts do?

A

must hatch and expand - grow until zona pellucida breaks.

trophoblast cells must multi rapidly + emybro enlognate

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11
Q

what is grastrulation?

A

due to proliferation and morphortic movement of the inner cell mass cells blastula with a single layer of cells to a gastrula containing multiple layers of cells.

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12
Q

describe the first stage of grastrulation?

A

formation of bilaminar emybro - epiblast = top
hypoblast = bottom
Hypoblast consists of the yolk sac (extra-emybroic endoderm) these extra-emybroic endoderm form the PLACENTA

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13
Q

What does the placenta consist of?

A

Yolk sac (earliest placenta)
amnion (surrounds emybro n foetus)
allantois (surrounds amnion)
chorion (outmost placental layer)

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14
Q

how is progesterone levels maintained until placenta is functional?

A

short CL lifespan means - prevention of luteolysis + continued CL function is crucial
in bovine - early ultrasound can look for CLs in scan

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15
Q

maintenance of progesterone secretion from CLs? how?

A

endometrial gland secretions support pregnancy throughout
progesterone reduces motile of tract and increase uterine growth
progesterone negative feedback on hypothalamic GnRH secretion: not surges!
no pre-ovulatory follicle development

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16
Q

in large animals = maintenance of progesterone secretion from CLs? how?

A

active luteolyss PGF2a secretion + action must be INHIBITED.

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17
Q

what is luteolysis inhibition?

A

causes active luteolysis to cause CL maintenance + prgestoen synthesis continue
emybroiuc hormones prevent PGF2a secretion into circulation

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18
Q

in dogs and cats how is there CL secretion controlled?

A

do not require extension of CL life-span, extra luteotrophic stimuli due to already long lifespan of CLs after ovulation
LH and prolactin
no difference in bitch progesterone hormone conc between pregnant and non-pregnant
But,,, an abrupt decline on day 65 of progesterone in pregnant bitch
Luteal phase is longer in non-pregnant bitch

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19
Q

describe normal luteolysis?

A

1) endometrial PGF2a synthesis - oxytocin binding to its receptor towards end of luteal phase in LA
2) initial oxytocin pulses come from precursor pituaity
3) oxytocin granules are secreted from large luteal cells in CL in reasons to first PGF2a pulse
4) ⬆️ PGF2a produced by endometrium ➡️ CL lysis

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20
Q

describe PGF2a secretion in normal luteolysis?

A

active luteolysis PGF2a secretion + action must be inhitbed - large luteal cells in the CL, secrete oxytocin and have PGF2a receptors

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21
Q

what is a polyoestris species ?

A

early emybro must initiate material recognition

prevent PGF2a release

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22
Q

what is a mono-oestrus species?

A

maternal recognisant not nessasary

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23
Q

describe the placenta?

A

extra-emybroic metal membrane
fluid filled
function - protects emybro/fetus devolpment
composed of yolk sac, amnion,allanrois,chroion

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24
Q

describe blastocysts?

A 
1) bilaminar emybric disc - origin of emybro - hypoblast = endoderm 
epiblast = emybroic ectoderm 
2) extra-emyrbpic membranes 
hypoblast = endoderm
epiblast = tropoblast
25
Q

describe the yolk sac?

A

mesoderm - extends form emybro
enters space between endoderm/trophectoderm
Blastocyte wall become trilaminarr omphaloplere
1) somatoplesure - trophectoderm + somatic mesoderm
2) splacnchonopleure - wall of yolk sac
3) extraemybryonic coelum/exocoelum - resulting cavity between somatic

26
Q

describe the amniotic sac?

A

formation - embryo sinks into somatphere , folds meet dorsally
Sac - contains amniotic fluid, surronds embryo + fetus
Yolk sac temporally fuses with chorion = choir-vitelline ‘placenta’

27
Q

describe the allantois?

A

diverticulum of hind gut
wall is splanchepleue, endoderm + splanchnic mesoderm
contains urine secretions + blood transudate
allantois fuses with chorion, forms chorio-allantoic placenta

28
Q

describe the chorionic villi?

A

protects surface of chorion,
diffuse - over majorly of chorion
placentas - mare etc

29
Q

what is the zonary placenta?

A

in a band (dog/carnivore) over the ovary

30
Q

what is the cotyledonary placenta?

A

arranged in formal areas (ruminants)

31
Q

what is the discoid placenta?

A

humans mainly

32
Q

name the 6 histological classification layers of placenta?

A

1) maternal endometrial endothelium
2) maternal connective tissue
3) maternal endometrial epithelium
4) fetal chorion
5) metal connective tissue
6) fetal endothelium. ( most animals)

33
Q

in carnivores name the 4 cell layers in the placenta?

A

1) maternal endothelium
2) fetal chorion
3) fatal connective tissue
4) fetal endothelium

more layers are shed after birth in carnivores so less layers.

34
Q

describe the umbilical cord?

A

fetal blood vessels in mesoderm, communicates with foetus via umbilical cord.
1) umbilical veins - Corry O2 + nutrients for feats
2) umbilical artery - carry fatal rate products form foetus
take deoxygenentaed blood back to aorta
3) allantoic duct - continues to bladder, drains urine form foetus.
4) ruminant present - haemoatopita function in some species.

35
Q

describe the pregnant sow anatomy?

A

spherical blastocysts dispersed along uterine horn by peristaltic movements.
inhibited maternal recognition
Diffuse epithelia-chorial: chronic villi join with endometrial villi (like velcro)
Villi also have interlocking microvilli.

36
Q

what is areolae?

A

absorptive area over endometrial glands = additional source

37
Q

describe the MARE pregnant anatomy?

A

Blastocyst enters uterus, stays spherical, hatches from zona pellucida
Very mobile!! covers full length of uterus.
prevents PGF2a release and therefore lysis - no counter current system, entire uterus be contracted

38
Q

what occurs at day 16 in the MARE pregnant?

A

blastocyst becomes enlongated in horn junction

side independent of CL

39
Q

what occurs at days 28-33 in MARE pregnancy?

A

allantois enlarges
yolk sac regresses
embryo moves dorsally

40
Q

how is the MARE pregnancy maintained?

A

single CL in uterus

@ day 35 = colic girdle forms ENDOMERTIAL CUPS

41
Q

what do endometrial cups function?

A

produce eCG/ PMSG
produce accessory CLs in ovary - help with ovulation and spontaneous lutenisation.
also has diffuse, epitheliochorial non-decimate placenta
these cups take over from ovary at day 140 during pregnancy.

42
Q

what are microcotylendons?

A

microvillous tufts prints only during pregnancy.

43
Q

why can’t the uterus support twins in a MARE?

A

if so abortion of entire pregnancy, 2 week foals die ultrasound diagnosis - 2Cls, 2 vesicles, not mobile/big enough etc

44
Q

pregnancy in ruminant anatomy?

A 
morula enters uterus day 4 - becomes blastocyst day 8, prevents PGF2a releases and therefore autolysis, counter current system so only 1 side used. 
cow has cotyledonary epithelium-chlorine non-decimate placenta
efficient maternal/fetal Exchange only at placentones - binucleoated giant cells fuse with uterine cells- secret placental lactose 
no villi!!
COW ultrasound (day 21)
Rectal ultrasound - looking for elongated vesicle - looking for corpus luteum (CLs) are very accurate.
45
Q

describe rectal palpation in cow for pregnancy?

A

6-8 weeks
detection of assymentirl uterus , ‘membrane slip’
CL on ovary on same side
Embryoic/foetal death = 10% of pregnancies - most by 45 days
5% = twins - Bilateral foetuses - located different horns in uterine.
if Male + female twins born, female will be infertile.

46
Q

describe ewe pregnancy anatomy?

A

cotyledonary epitheliochorial non-decimate placenta
twins a lot more common - in different horns
caruncles convey/dense shaped.

47
Q

histology of ewe pregnancy anatomy?

A

similar to cow, arcade zone
haemorrhage in space before martial + foetal villi.
allows phagocytosis of maternal blood cells

48
Q

what is PDing?

A

pregnancy diagnosis (scanning) - 70-105days in
gives foetal number, management of late gestation
200 ewe per hour
VENTRAL ABDOMEN
Able to determine number/feed needed/spilt sheep into group sizes/BCS sheep etc

49
Q

describe dog/cat pregnancy anatomy?

A

both have Zonary, endothelia-chorial decimate placenta
they are both litter producing.- embryonic vesicles mobile till d13, no material recognition of pregnancy.
Ultrasound PD - 28 days after last mating, no need to report exam - palpation 21-23d not all dogs tho

50
Q

what is a deciduate placenta?

A

maternal part is shed on delivery of litter
green in bitch
brown in cat(queen)

51
Q

what hormones are used within pregnancy?

A

progesterone - prepare tract for pregnancy
oestridaiol - maturation and release of egg, thicken of uterus lining
eCG - produced by mares - used to enhance rpeoducion
placental lactogens - breaks down fats from mother, insulin resistance and carbohydrate intolerance in the mother.

52
Q

does placenta take over production of CLs from progesterone?

A

yes, it helps to support pregnancy.

53
Q

in ruminants, progesterone are the unicellular + differentiating giant trophoblast cells
true or false?

A

true - placenta produces oestrogens important for placental growth, blood flow and fetal growth.

54
Q

at day 35-120 in the mare, what does eCG do?

A

eCG has a LH-like activity + stimulates luteniziation or even ovulation - more accessory CLs in ovaries presnsy

55
Q

What are placental lactogens important for?

A

maternal glucose metabolism
‘uterine milk’ production from endometrial glands
mammogenesis (mammary gland)
also
maternal oxygen + fetal CO2 Exchange possible due to foetal haemoglobin has a higher affinity to O2 ay lower O2 Partial pressure.

56
Q

what is an allograft and how does it have an immunological fucntion?

A

an allograft is a transplant of an organ or tissue from one individual to another of the same species with a different genotype
in mare - we see localised immune ration and sometimes fatal RBC rejection

57
Q

describe maternal rejection of faetal cells in the mare?

A

a chorionic girdle forms around the periphery of the yolk sac.

1) endometrial cups + rejected
2) Rhesus positive (Ag on RBC) human feted leads to haemolytic antibody response in Rh negative mothers
3) Isohaemolytic anaemia - foal ingests haemolytic maternal Ab through colostrum + develops anaemia 2-3d later

58
Q

how do placental hormones affect maternal metabolism + endocrinology to support fatal devoplemt?

A 
placenta ➡️ oestradiol, progestrone, placenta lactogens
➡️ Bones (⬆️PTH) 
➡️ Kidneys (⬆️GFR,⬆️aldosterone) 
➡️ Thyroid gland (⬆️TSH, ⬆️T3/T4)
➡️pancreas = glucagon ⬆️, insulin ⬇️
➡️ Liver = Poetin sysntheis ⬆️
59
Q

how can levels of Relaxin be used to determine a bitch pregnancy?

A

Relaxin release at 21-26d of gestation - measures of relaxin can be measured and determine pregnancy.

BVMS Module 5 (4 decks)

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