Placentation, Gestation, Parturition Flashcards
Temporary, metabolically active organ providing support and protection for the developing embryo/fetus, with maternal and fetal components.
placenta
Outermost layer of the placenta
Chorion
Cavity immediately surrounding the embryo/fetus
Amnion
Cavity originating as an outpouching of the hindgut, and that is continuous with the urachus
Allantois
Classification of placenta by shape
Diffuse - horses, pigs
Cotyledonary - cow, sheep, goats
Zonary - dog, cat
Discoid - human, mouse
Most intimate type of placenta with only one area of attachment to mother
Discoid
Classification of placenta by degree of invasiveness
Epitheliochorial - 6 layers with intact membranes on both sides. Horse and pig.
Syndesmochorial - Fetal-maternal syncytium.
Maternal epithelial layer missing. Cow and sheep.
Endotheliochorial - 5 layers. Dog and Cat. No uterine epithelial layer.
Hemochorial - 3 ;ayers, only fetal layers present.
Which type of placenta allows immunoglobulins, and also pathogens, to transfer to the embryo?
Hemochorial
Classification of placenta by intimacy of attachment
Adeciduate - horse, pig, ruminants. Loose villi, endometrium not disrupted during parturition.
Deciduate - dog, cat, human. Villi pull free and cause erosion of the endometrium during parturition.
What type of animal has a cotyledonary, chorioallantoic, epitheliochorial/syndesmochorial, and adeciduate placenta?
Bovine
What type of animal has a diffuse,chorioallantoic, epitheliochorial, and adeciduate placenta?
Equine
What type of animal has a zonary, chorioallantoic, endotheliochorial, and deciduate placent?
Canine
eCG in the equine is produced by what structures in the uterine wall?
endometrial cups
Structure in the equine where the placenta lays against the cervix.
Cervical star
Placentomes are a feature of the _____ placenta where exchange occurs, and are made up of the cotyledon and the caruncle.
bovine
Species that have necrotic tips on the plaenta
cows, pigs
In the canine, _____ _____ is seen on the edges of the zonary placenta
marginal hematoma
What type of animal’s placenta has a 4th membrane (epithelion) for protection from friction and dehydration?
Camelids
Fetal period in the bovine
After day 45
Fetus has organs and placenta
Period of growth (mitosis)
*at this stage will look like a small cow
Hormones produced by the placenta
Progesterone Estrogen Relaxin Placental lactogen Chorionic gonadotrophin Prolactin
Accessory corpora lutea, which produce progesterone and are necessary to maintain pregnancy, are found in what species?
Equine
In late pregnancy in the equine, ______ interacts with progesterone receptors
5-alpha-pregnanes
Functions of fetal fluids
Protection
Nutrient reservoir
Water reservoir - friction reduction
_______ is an absolute requirement for mammalian pregnancy.
Progesterone
Where does progesterone come from?
Ovary
Placenta
Functions of progesterone
placental development and function
myometrial quiescence
cervical closure
immune mediation
In what species is the corpus luteum the only source of progesterone?
Goat and pig
During pregnancy, the uterine blood flow, cardiac output, and blood volume ______, but the hematocrit ______.
increase, decreases
Increased insulin resistance during pregnancy can lead to
gestational diabetes
laminitis in horses
frank diabetes
Main trigger for parturition
Fetal hypothalamic-pituitary-adrenal axis
CRH > ACTH > cortisol release within the fetus
With elevated fetal cortisol, final maturation of these 3 organs occurs
lungs, kidneys, brain
Elevated fetal cortisol levels induce _______, which lyses the CL to bring down progesterone levels and increase estrogen levels so the uterus will start contracting.
P450 enzymes
Functions of estrogen during parturition
Synergistic with relaxin
Breaks down bonds in collagen (softening of ligaments, cervical ripening)
Myometrial activity involves
smooth muscle contraction (Ca++, MLCK activation and phosphorylation)
PGF2a and oxytocin (oxytocin will help muscles contract when they get tired)
In the neonate, the main stimulus for respiratory stimulation is
Cold touch
Respiratory rhythm is generated where?
ventrolateral medulla
