15 – Key Hormones and Fetal Fluids Flashcards
1
Q
Marked placental growth must occur PRIOR to
A
- Significant fetal growth
- *increased placental blood vessel growth and vasodilation
- Areolar growth helps with transport of nutrients, gases, growth promoting factors
2
Q
Progesterone during gestation
A
- Stimulates ENDOMETRIAL GROWTH and particularly GLAND DEVELOPMENT AND SECRETIONS
- *also produces PROGESTERONE BLOCK
3
Q
Progesterone block
A
- Inhibiting uterine contractions (quiescence)
- Absolute levels vary among species
4
Q
Luteo-placental shift
A
- In some species
- Placental progesterone productions takes over from CL to maintain pregnancy
- Ex. horses, humans
5
Q
Species where removal of ovaries is followed by abortion
A
- Cows (after 8months, would be okay)
- Pigs
- Goats
- Dogs
- Alpacas and Llamas
- Rabbits
- *placenta does NOT produce enough P4 or dogs: no P4
6
Q
Cats and P4 compensation
A
- No luteo-placental shift
- Placenta can produce enough P4 to compensate for loss if ovaries removed
- *CL is present for most of the pregnancy
7
Q
Estrogens/estradiol during gestation
A
- Endometrial growth
- Important product of placenta (especially during last part)
- *peak in most species=indicates close to parturition period
- **INCREASED levels=promote LABOUR
- Mare and humans it gradually increases throughout (need estrodial precursors)
8
Q
Placental lactogen
A
- Also called chorionic somatomammotropin
- Produced by TROPHOBLASTS (in ruminants: secreted by BNGC and TNCs)
9
Q
Placental lactogen is found in (species)
A
- Rodents
- Sheep
- Cow
- Goat
- Humans
10
Q
Placental lactogen (chorionic somatomammotropin) levels
A
- Maternal: steady increase in levels up to Parturition
- Fetus: varies
o Sheep: remains constant
o Bovine: decline throughout
11
Q
Placental lactogen (chorionic somatomammotropin) function to dam
A
- *growth hormone in function
- Stimulates mammary gland growth/development
12
Q
Placental lactogen (chorionic somatomammotropin) function on fetus growth
A
- Due to induction of growth promoting factors (ex. insulin GFs)
- Anti-insulin effect on dam=frees up maternal glucose stores for fetus
- Stimulates AA uptake
13
Q
PAG production during gestation
A
- As early as day 24
- Peak just before parturition
- *different forms are marked by alterations in their glycosylation=multiple unclear roles
14
Q
PAG functions during gestation
A
- Process or cleave GFs
- Immunomodulatory functions
- Luteotropic role via increased stimulation of PGE2
15
Q
PAGs during gestation: measure in ruminants
A
- In serum or plasma using ELISA
- *confirm pregnancy in ruminants
16
Q
Relaxin during gestation in equids (mare)
A
- Rise quickly and reach peak around mid-pregnancy to parturition
- Drop markedly after parturition
17
Q
Relaxin during gestation in sows
A
- Maternal serum levels INCREASE dramatically LATE in pregnancy prior to parturition
- Stored within CL and released upon luteolysis as Parturition nears
18
Q
Actions of relaxin
A
- Softening or relaxation of pelvic ligaments (ex. mare and women)
- Growth and relaxation of uterine muscle during pregnancy
- Cervical relaxation for parturition
19
Q
Relaxin during gestation in dog
A
- 20-30days, max at 5-7weeks
- Undetectable in non-pregnant
- *levels are basis of pregnancy test in dogs
20
Q
Relaxin during gestation in cat
A
- Appears at 3rd week
- *markedly INCREASES then DECLINING just before parturition
- Could be used for pregnancy diagnosis: kits are in development
21
Q
Actions of relaxin in dog and cat
A
- INHIBIT uterine activity and relax pelvic ligaments
22
Q
Glucocorticoids
A
- Steroid class produced by adrenal glands
- Primarily cortisol in horses, ruminants, pigs, dogs and cats
o Regulate gene expression, transcription and translation - *produced on demand
23
Q
What is the name of the cortisol carrier in the blood?
A
- Corticosteroid binding globulin (CBG)
24
Q
Cortisol levels in ruminants (maternal)
A
- Total maternal cortisol does not change over majority of gestation
- *SPIKES AT PARTURITION
25
Cortisol levels in horses (maternal)
- Fluctuates
- INCREASES JUST BEFORE PARTURITION
26
Cortisol levels in pigs (maternal)
- Little change over gestation/birth
27
Fetal cortisol levels in ruminants and pigs
- Fetal adrenals produce almost all their own cortisol by late pregnancy
o Why maternal levels don’t change as fetus is self-sufficient
28
Fetal cortisol levels in horses
- Fetal adrenals mature later on, so maternal levels may supplement fetal production
29
Cortisol actions**
- Mediating maternal energy demand (free up plasma glucose, anti-insulin effect)
- Triggering maturation of fetal organs
- Initiating parturition
30
What are the 4 fetal membranes?
- Yolk sac
- Chorion
- Amnion
- Allantois
31
Yolk sac
- First formed
- Nutrition (birds and reptiles)
- *first hematopoietic organ and source of primordial germ cells (mammals)
32
Membrane arrangement: at mid-gestation
- Ruminants + pigs: flatter/anchor
- Horses + carnivores: circular/tube
33
Chorion
- Outermost extra-embryonic membrane
- Trophectoderm (near embryonic disc) and somatic mesoderm
- *GAS EXCHANGE, RESPIRATION
34
Amnion
- Most evolutionary
- *AQUATIC MICROENVIRONMENT
35
Allantois
- STORAGE BIN
- MEDIATES GAS EXCHANGE
- Size in mammals depends on how well N wastes are removed (can fill entire extra-embryonic coelom)
36
Total volumes of amniotic and allantoic fluids during pregnancy
- *generally INCREASE
37
Ruminants and mare fetal fluid levels
- Allantoic increases in 1st third and last third
- Amniotic: 2nd third
38
Sow fetal fluid levels
- Allantoic: rises quickly by 30d, max by 60d then declines toward term
- Amniotic: gradually increases, max 60d then declines toward term
39
Amniotic fluid
- Water and solute from maternal plasma
- Secretions from developing respiratory tract enter amniotic fluid, but fluids and solutes can also cross from amnion cavity to fetus
- Once fetal kidneys function=fetal urine contributes
- Fetal swallowing contributes FLUID MOVEMENT INTO LUNG AND GIT
40
Amniotic fluid composition
- CHO
- Proteins
- Lipids
- Enzymes
- Hormones
- GFs
- Electrolytes
- AA
- Water
41
Amniotic fluid roles
- Prevent desiccation
- Shock absorber
- Nutrition
- Innate immunity
- Development
- Aiding parturition
42
Allantois fluid
- Once kidneys functional, urine goes into it
- Reservoir for nutrients
43
Allantois fluid composition
- Hormones
- *Fructose
- Glucose
- Electrolytes
- AA (ex. arginine, glutamine)
44
Role of allantois fluid
- Shock absorber
- Nutrition: can metabolize stored nutrients for benefit of placental and conceptus growth
45
Disposition of fetal sacs in polytocous species (cats, dogs, pigs)
- Distribution along length of uterine horns
- Sometimes nearest one to uterine body extends into both horns
46
Disposition of fetal sacs in monotocous species (ruminants)
- Fetus with amnion and large part of chorioallantois in uterine horn adjacent to ovary with CL
- Small portion of chorioallantois into other horn
47
Disposition of fetal sacs in monotocous species (horses)
- Majority of chorioallantois and amnion in gravid horn with continuation into uterine body
- Small, narrow portion of chorioallantois pushes into NON-gravid horn
48
Hydrops
- Excessive accumulation of fetal fluids in either amnion or allantois in cattle
- Ex. hydrallantois or hydramnion
49
Hydrallantois
- 6-9months gestation with up to 40x excess fluid
- *presents as progressive distension of R. abdominal wall
- **thought to be a result of placental abnormalities
50
Hydramnion
- 8-10x normal fluid level associated with malformation of digestive system
- Rare in sheep, pigs, dogs, cats
- Not reported in horses
51
3 main methods of pregnancy diagnosis in vet med
- Palpation (need enough fetal development)
- hormone measurements (ex. PAGs, eCG, relaxin)
- ultrasonography=most IMMEDIATE, DIRECT, ACCURATE
52
Ultrasonography and fetal fluids
- takes advantage of early increases in allantoic fluid volumes and amniotic fluid volumes
o end of first month: ewe, cow, mare
o d25-35: dogs, cats
- *B-mode most commonly used
