Exam 5: Placentation, Gestation, and Parturition Flashcards
What is the placenta?
Fusion of fetal membranes to endometrium
Organ of physiologic exchange
What does the size and function of the placenta change with?
Stage of pregnancy
When is the placenta expelled?
After parturition
How is the placenta classified?
Gross shape and distribution of villi
Microscopic structure of feto-maternal barrier
Loss of maternal tissue at parturition
What is the function of villi?
To bring fetal vessels into close proximity to maternal blood vessels
What kind of placenta do mares and sows have?
Diffuse
What kind of placenta do ewes, does, and cows have?
Cotyledonary
What kind of placenta do bitches and queens have?
Zonary
What kind of placenta do primates and rodents have?
Discoid
Describe diffuse placenta
Attachement dispersed everywhere
Describe cotyledonary placenta
Multiple focal areas of attachment
Describe zonary placenta
Placenta attaches in a specific circular zone all around the fetus
Describe discoid placenta
Very large, single area of attachment where all of the exchange occurs
What forms placentomes?
The fusing of fetal cotyledons and maternal carunlces
What are maternal caruncles?
Specialized projections of uterine mucosa
What are the maternal caruncles like in the cow?
Convex
What are the maternal caruncles like in the ewe and doe?
Concave
What is the name given to the functional unit of a cotyledonary placenta?
Placentome
What are the degrees of invasiveness?
Epitheliochorial
Endotheliochorial
Hemochorial
Describe epitheliochroial
Pig, horse, cow, ewe, and doe Least intimate (more layers), both maternal and fetal epithelium
Describe endotheliochorial
Dog and cat
Complete erosion of endometrial epithelium
Fewer layers
Describe hemochorial
Primates and rodents
Chorionic epithelium is in direct apposition to maternal pools of blood
Most intimate
What are the degrees of intimacy?
Deciduate
Adeciduate