Placentation Flashcards
the placental has 2 components, 1. the fetal part that develops from the __ and 2. the maternal part that is derived from the __
chorionic sac, endometrium
the placental has a selective __ that does __ prevent crossing of certain viruses, toxins, parasites
placental barrier, NOT
the placenta is an __ organ secreting hormones necessary for __
endocrine, pregnancy
progesterone from the placenta
- promotes endometrial growth
- suppresses myometrial contractions
- promotes alveolar development in the mammary gland
CL is the original source in all species
estrogen from the placenta
“tissue building”
- myometrial growth and increase uterine vascular proliferation and mammary ductal growth
- estrogen also causes increased sodium reabsorption by mothers kidney renal tubules -> increases blood volume
the fetal gonads in horses are grossly __ during gestation as a result of __ precursors
hypertrophied, estrogen
placental relaxin from the placenta
present in carnivores and horses to relaxes the cervix, pubic symphysis and ligaments
placental relaxin is present in carnivores and horses while in cows, sows, and primates it is partially made by the __
CL
histotrophic nutrition
uterine glands -> nutrients -> diffusion-> embryo
chorionic placenta -> yolk sac
hemotrophic nutrition
- fetomaternal blood exchange
- allantoic placenta
amnion and chorion are made of __ and __
somatic mesoderm and trophectoderm (ectoderm)
allantois and yolk sac are made of __ and __
splanchnic mesoderm and hypoblast (endoderm)
implantation in the equine is at the junction of the __ with the __
uterine horn, body
yolk sac
temporary structure capable of histotrophic nutrition thats important during attachment and a source of primordial germ cells
chorion
most external!
- abuts endometrium provides contact between the embryo and external environment
- chorion helps attach early embryo to uterus
chorion consists of __ and associated __
trophoblasts (ectoderm), somatic mesoderm
amnion
immediately surrounds and contains embryo and amniotic fluid
the aqueous fluid provides …?
cushion, movement, prevents adhesion of fetus with amniotic membrane and practice swallowing, gut contractions and breathing
allantois
diverticulum of the hind gut
allantois in carnivores, horses
tube shaped, grows completely between the amnion and chorion
amniotic plaques
normal mineral and sloughed cellular deposits on the surface of umbilical cord or other membrane -> white plaques
-> mostly seen in equine and ruminants
Hippomanes (allantoic calculi)
found in allantoic fluid from day 85 with soft concentric layers
hydrops allantois
excessive allantoic fluid in cattle and horses
hydrops amnion
excessive amniotic fluid
olioghydramnios
abnormally low amniotic fluid
endometrial cups
Equine only!
- normal and temporary during days 35-125 and then regress
- certain parts of the chorion detach and invade endometrium
- secrete equine chorionic gonadotropin
chorionic placenta is __ and is only seen in __ until the allantois is formed
avascular, carnivores
the choriovitelline (yolk sac) is retained for longer in the __ than the dog
equine
the chorioallantoic placenta is the __ placenta of domestic animals and forms a __ membrane
permanent, trilaminar (trophoblasts, mesoderm, endoderm)
the amnion and the chorion __ fuse in the horse and dog and __ fuse in the pig and ruminant
DO NOT, DO
in all animals except carnivores the degree of placental invasion into the endometrium is __ meaning it will ___ separate after birth
non-deciduate, easily
deciduate placentas are not easily separated because the __ fuse with the erode endometrium
chorionic villi
the sow, mare and camelids have a __ placenta that covers the entire surface of the __
diffuse, uterus
what is a red bag abortion?
premature placental separation
- appearance of the cervical star at the vulva and the enclosed legs of the fetus
- the fetus is often delivered within the placenta, with the chorionic side of the placenta still on the outside
maternal caruncles + fetal cotyledons = __
placentomes (ruminants)
zonary placenta
in carnivores where contact area is ring/belt like band with marginal hematomas providing a source of iron
