Placental function

Question 1

What are the 3 main roles of placenta?

Answer 1

• maintenance of pregnancy (some species)
• nutrition
• immune function

Question 2

In what species does the placenta take over progesterone production to maintain pregnancy?

Answer 2

cow, ewe, mare, queen

Question 3

At what stage does the placenta take over progesterone production in the cow?

Answer 3

Late stage - 200days

Question 4

At what stage does the placenta take over progesterone production in the ewe?

Answer 4

Early stage - 50 days

Question 5

At what stage does the placenta take over progesterone production in the mare?

Answer 5

Early stage 70-120 days

Question 6

At what stage does the placenta take over progesterone production in the cat?

Answer 6

Late stage - 50 days

Question 7

What other hormone is produced by the placenta?

Answer 7

oestradiol

Question 8

Describe why and how oestradiol is produced during pregnancy

Answer 8

• for proliferation of foetal cells and growth of foetus
• foetus produces androgens and placenta acquires ability to aromatise these to oestron, oestradiol or oestriol
• oestrone can be measured in maternal fluids and is an indication of healthy placenta
• oestriol can be measured and is an indication of feotal health

Question 9

What extra hormone is produced by the mare and what is its function?

Answer 9

• equine chorionic gonadotropin (eCG)
• produced by endometrial cups
• has LH activity on ovaries and causes more follicles to luteinise producing accessory CLs

Question 10

Describe the nutritional function of the placenta

Answer 10

• produes lactogens which have 2 functions - somatotrophin-like-growth hormone and lactotrop-like prolactin like activity
• maintain high plasma [glucose] to provide the foetus with enough glucose for growth
• placenta is exchange area for oxygen