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What are the four main types of placentae classified by the distribution of chorionic villi?
What are the four main types of placentae classified by the distribution of chorionic villi?
Diffuse, cotyledonary, zonary, and discoid.
Briefly explain the significance of the separation of maternal and fetal circulation in the placenta.
Briefly explain the significance of the separation of maternal and fetal circulation in the placenta.
It prevents mixing of blood, allowing for efficient exchange of nutrients and waste between the mother and fetus.
What histological indicators might suggest pathology in placental tissues?
What histological indicators might suggest pathology in placental tissues?
Presence of necrotic tissue, unusual inflammation, or abnormal vascular structures.
How do cotyledonary placentas differ functionally from diffuse placentas?
How do cotyledonary placentas differ functionally from diffuse placentas?
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Describe the role of hormone signaling in both male and female reproductive tracts during the reproductive cycle.
Describe the role of hormone signaling in both male and female reproductive tracts during the reproductive cycle.
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How many tissue layers separate the fetal and maternal circulation in a complete placenta?
How many tissue layers separate the fetal and maternal circulation in a complete placenta?
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What is the potential consequence if fetal blood enters the maternal circulation?
What is the potential consequence if fetal blood enters the maternal circulation?
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What type of placenta is characterized as cotyledonary?
What type of placenta is characterized as cotyledonary?
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Which layer is absent in the fetal and maternal circulation separation when there are 5 tissue layers?
Which layer is absent in the fetal and maternal circulation separation when there are 5 tissue layers?
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What is the definitive sign of pregnancy in cattle, as indicated in the context?
What is the definitive sign of pregnancy in cattle, as indicated in the context?
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Study Notes
Placentae (Specific)
- Placentae are classified by the distribution of chorionic villi
- Diffuse: even distribution across the entire chorionic surface
- Cotyledonary: discrete round patches of villi forming cotyledons on the chorion, connected to endometrial caruncles
- Zonary: prominent round transfer zone of villi as a central band, edges form pigmented area with haemorrhage and necrosis
- Discoid: discrete disc of villi on one side
Placental Distribution
- Placentae are also classified by their invasiveness, which determines the number of tissue layers between the fetal and maternal circulation (fetal and maternal separation)
- Epitheliochorial: 6 layers separating maternal and fetal circulation.
- Endotheliochorial: 5 layers separating maternal and fetal circulation.
- Hemochorial: 3 layers separating maternal and fetal circulation.
Placental Types by Species
-
Cattle (cows):
- Cotyledonary
- Epitheliochorial
- Convex caruncles
- 70-120 cotyledons, increasing in size through gestation. Placentome = fetal cotyledon + maternal caruncle
-
Sheep (ewes):
- Cotyledonary
- Epitheliochorial
- Concave caruncles.
-
Horses (mares):
- Diffuse
- Epitheliochorial
- "F" shaped placenta
- Microcotyledons
- Endometrial cups
- Placental cells invade endometrium
- Transient structures (~d40-150).
- Cervical star
- Large, white avilous region.
-
Pigs (sows):
- Diffuse
- Epitheliochorial
- Simple chorionic villi
- Smooth surface
-
Dogs (bitches):
- Zonary
- Endotheliochorial
- Highly invasive villi in the transfer zone
- Marginal band of haematoma
- Relatively avascular rest of the chorioallantois
-
Cats (queens):
- Zonary
- Endotheliochorial
- Highly invasive villi in the transfer zone
- Relatively small band of haematoma
- Relatively avascular remainder of chorioallantois
-
Fetal/maternal blood NEVER mixes directly
-
Fetal blood entering maternal circulation can be treated as a foreign antigen, causing sensitization and neonatal isoerythrolysis for offspring.
Histology of Placenta
- Ruminants: have both regular and binucleated trophoblasts, invade the endometrium and produce placental lactogens and placental growth factors
- Chronic trophoblast cells are typically cuboidal-columnar
Histopathology
- Examples of histopathology include necrosis (debris) and fungal hyphae, congestion in the chorioallantois, fibrinous exudate, neutrophilic infiltrate and Gram +ve bacteria.
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Description
Explore the various classifications of placentae based on chorionic villi distribution and invasiveness. This quiz covers different placental types found in species including cattle, highlighting their unique characteristics. Test your knowledge on the complexities of placental structures!
