Flashcards in Lecture 11: Placentation (Kelleman) Deck (46)
mammalian type: prototherian group
- egg-laying mammals.
- examples: platypus echidnas
- they do not have a placenta
mammalian type: metatherian
- they do not have a true placenta - they have a "choriovitelline placenta" aka vascularized yolk sac.
- examples: marsupials - kangaroo and opossum
mammalian type: eutherian
- possess a chorioallantoic placenta (aka the "true" placenta)
- most mammals you think of - dog, cat, horse, etc.
vascular organ formed in uterus during pregnancy, consisting of BOTH maternal and embryonic/fetal tissues. It provides oxygen and nutrients for fetus and transfers waste products from the fetal to the maternal blood circulation.
membranes that function for the protection or nourishment or respiration or excretion of a developing fetus
what day does implantation (attachment of the placenta to the uterus) occur in the cow?
day 30 -35
what day does implantation (attachment of the placenta to the uterus) occur in the sow?
day 12 - 20
what day does implantation (attachment of the placenta to the uterus) occur in the ewe?
day 18 - 20
what day does implantation (attachment of the placenta to the uterus) occur in the mare?
day 50 - 60
what is the meaning of the latin root of the word "placenta?"
latin root of placenta = "cake"
Name 5 roles of the placenta
1. nutrient exchange
2. gas exchange
3. stores waste
5. endocrine organ
What are the 4 Fetal Membranes that make up the placenta and what are their functions?
1. yolk sac - early nutrition
2. amnion - nutrient exchange, protection, waste
3. allantois - waste, gas exchange
4. chorion - maternal interface, nutrient exchange
How are placentas classified? (3 classifications)
1. distribution of contact areas
2. tissue layers separating maternal and fetal blood
3. maternal tissue lost at birth
what are the 4 different types of choionic villi (a contact area between fetus and mom)
what are the characteristics of a diffuse placenta?
maternal and fetal intimate contact is found throughout the placenta
characteristics of the cotyledonary type placenta
specialized areas of the endometrium (caruncles) are in contact with vascularized portions of the chorion (cotyledon). the combined structural unit of the fetal cotyledon with the maternal caruncle is called the placentome.
what makes up a placentome?
caruncle (maternal side) + cotyledon (fetal chorion) = placentome
characteristics of the zonary placenta
the most intimate contact is found in a "belt-like" area encircling the conceptus
describe the characteristics of the discoid placenta
the itneraction is found in one or two round areas
6 layers separating maternal and fetal circulation - starting from most internal fetal side to most internal maternal side?
2. connective tissue
5. connective tissue
which layer is missing in a 5 layered placenta?
the maternal epithelium
what are the missing layers in a 4-layered placenta?
the maternal epithelium and maternal connective tissue
what are the missing layers in a 3-layered placenta?
all maternal layers - the maternal epithelium, maternal connective tissue and maternal endothelium
what is the term for a 3-layered placenta?
what is the term for a 4-5 layered placenta?
what is the term for a 5-6 layered placenta?
bonus Q: what is the old term for this?
old term = syndesmochorial
what is the term for a 6-layered placenta?
is a 6 layered placenta.
But it is also used as a sort of all-encompassing description for a placenta that is either 5 or 6 layers.
characteristics of an epitheliochorial placenta and animals that have it
- the chorion is apposed to (next to/touching) the maternal epithelium. it is the least invasive of the types.
- mare, sow, hembra (camelids)