Exam 4: Placentation Flashcards
(16 cards)
What are eutherian mammals
Mammals with placentas
Functional unit of the placenta
Chorionic villi
Small projections into the endometrium where exchange of nutrients takes place
Types of placentas
Diffuse, cotyledonary, zonary, discoid
Species with a diffuse placenta
Sow
Mare
Species with a cotyledonary placenta
Convex: cow, giraffe (tree goes up from caruncle)
Concave: sheep, goat (tree goes down from chorionic tissue)
Species with a zonary placenta
Dogs
Zones of a zonary placenta
- Transfer zone (TZ)
- Pigment zone (PZ)
- Allantochorion (AZ)
Species with a discoid placenta
Primates
Species with epitheliochorial placentas
Pigs, horses, ruminants
Species with endotheliochorial placentas
Dogs and cats
Species with a hemochorial placenta
Primates and rodents
5 mechanisms of exchange in the placenta
- Simple diffusion: H2O and gases
- Facilitated diffusion: specific protein transporters- amino acids and glucose
- Active transport: ATP- transport of NA+/K+ and Ca2+
- Pinocytosis/endocytosis: IgG
- Leakage: red blood cells
What compounds can cross the placenta
Lipids and proteins (with difficulty)
Glucose and H2O (very easily)
Toxic substances: alcohol, antibiotics, tetracyclines, opiates, amphetamines, LSD, lithium
Bacteria: syphilis
Viruses: herpes and HIV
6 hormones found in the placenta
Progesterone (6-10 ng/ml)
Estrogen (aromatization, multiple functions)
hCG abd eCG (clinical importance)
Placental lactogen (bifunctional- stimulate growth hormones and prolactin receptor)
Interpherons
Relaxin
Where is 17-alpha progesterone found
Exclusively ovarian
3 factors that prevent rejection of the fetus
- Antigenic status: gametes and embryos do not express MHC antigens
- Immunoregulation of placenta and decidua: production of immuno-suppressive products and non-T non-B suppressor cells
- Hormonal regulation of lymphocytic response: progesterone and 1,25 dihydroxy-cholecalciferol have immunosuppressive properties, block proliferation and function of NK cells and other lymphocytes
