Placentation Flashcards
What are the four functions of the placenta?
- Exchange.
- Endocrine.
- Chemical Protection.
- Physical Protection.
What is the exchange function of the placenta?
- O2 and CO2 exchange.
- Waste products.
- Nutrients.
What is the endocrine function of the placenta?
- Estrogen.
- P4.
- eCG (equine).
- hCG (human).
- Placental lactogen (PL).
*Transient.
What is the chemical protection function of the placenta?
- Immunosuppression.*
- Prevents infiltration by maternal defenses.*
- Filter toxins and microorganisms.
*Prevents the maternal immune system from attacking the embryo.
What is the physical protection function of the placenta?
Shock absorber.
What is gastrulation?
When the single-layer blastula becomes a three-layer structure.
List the gastrulation layers in the order in which they form.
- Endoderm.
- Ectoderm.
- Mesoderm.
What is the endoderm?
The layer that lines the trophoblast cells and gives rise to the yolk sac.
What is the ectoderm?
The layer that covers the trophectoderm.
What is the mesoderm?
The layer that forms between the ectoderm and the yolk sac. Becomes the allantoic portion of the placenta.
What tissues are formed by the ectoderm?
- CNS.
- External repro. anatomy (penis, scrotum, Cowper’s gland, posterior vagina, clitoris).
- Sense organs.
- Hooves.
- Mammary glands.
- Hair.
- Sweat glands.
- Skin.
What tissues are formed from the mesoderm?
- Circulatory system.
- The rest of the reproductive tract.
- Skeletal.
- Urinary ducts.
- Muscle.
- Kidneys.
- Reproductive tracts.
What tissues are formed from the endoderm?
- Primordial germ cells.
- Digestive.
- Other glands.
- Liver.
- Thyroid.
- Lungs.
- Pancreas.
List the four placental membranes from innermost to outermost.
- Yolk Sac.
- Amnion.
- Allantois.
- Chorion.
What is the function of the yolk sac in birds?
To nourish the embryo.
What is the function of the yolk sac in mammals?
Acts as a source of blood cells and primordial germ cells.
*Atrophies.
What are the characteristics of the amnion?
- Non-vascular* and fluid-filled.
- Protective cushion.
- Ruptures at birth.
- Contains fluid produced by the fetus.
*Except equines.
What are the characteristics of the allantois?
- Contains blood vessels that attach to the umbilical cord.
- Fuses with the chorion to form the allantochorion or the chorioallantois. When ruptured at birth, fluid leaks out.
- Brings blood vessels to the chorion.
What are the characteristics of the chorion?
- Attachment to the mother.
What are the four types of placental attachment, and which animal(s) does each belong to?
- Cotyledonary: Cattle, sheep.
- Discoid: Human, non-human primate.
- Zonary: Dog, cat.
- Diffuse: Horse, pig.
How many cotyledons do cows have?
70-120.
How many cotyledons do ewes have?
90-100.
What is the shape of the cow placentome?
Convex.
What is the shape of the ewe placentome?
Concave.