10.1. Hormonal Regulation of Pregnancy

Question 1

hormones involved in regulation of pregnancy?

Answer 1

1. progesterone
2. relaxin
3. prolactin
4. placental lactogen
5. chorionic somatotropin

Question 2

• primary hormone
• ↑ to maintain pregnancy

Answer 2

progesterone

Question 3

(2) animals which major source of progesterone is in the CORPEUS LUTEUM (CL)

the rest is in PLACENTA, CL

Answer 3

1. sow
2. doe

Question 4

Progesterone in pregnant DOG:

beginning: _____
during: _____
after parturition: _____

Answer 4

beginning: increases
during: plateu (maintained)
after parturition: declines

Question 5

Progesterone profiles in pregnant & pseudopregnant bitches are indistinguishable until late in gestation (>30
days of pregnancy) or ______

Answer 5

diestrus

Question 6

Pregnant & pseudopregnant cats has SAME progesterone
levels first ____ weeks after ovulation

Answer 6

first 3 weeks

Question 7

progesterone concentrations _____ in
pseudopregnant cats, but increase in pregnant cats

Answer 7

decline

Question 8

In pregnant MARE, they have very low ___-___

Answer 8

PGF2-alpha

Question 9

In pregnant MARE if they are not truly pregnant, progesterone declines, PGF2-alpha production leads to _____

Answer 9

luteolysis

Question 10

Function of what hormone in pregnancy?

1. stimulates endometrial growth
2. promotes oviduct & endometrial gland secretion (source of nutrients for embryo)
3. inhibits uterine contraction (maintenance uterine quiescence to allow fetal dev)
4. dev of tubular tract & alveoli of mammary gland

Answer 10

progesterone

Question 11

• this is secreted by placenta (trophoblasts)
• maintains uterine quiescence (together with progesterone)
• increases throughout pregnancy starting end of 3rd week of gestation

Answer 11

relaxin

Question 12

when is relaxin secretion in Dogs & Cats

Answer 12

Cat: end of 2nd week
Dog: end of 3rd week

Question 13

secreted by leutotrophs in the anterior pituitary gland (APG)

Answer 13

prolactin

Question 14

target site of prolactin

Answer 14

mammary glands

Question 15

Functions of what hormone?

a. initiates & maintains milk synthesis
b. regulates maternal behavior

Answer 15

prolactin

Question 16

• is secreted by placenta (trophoblasts)
• in goat, sheep, cow

Answer 16

placental lactogen / chorionic somatotropin

Question 17

Function of what hormone?

a. somatotropin-like effect (growth hormone [GH], insulin-like growth factor [IGF])

b. lactogenic activity - dev of mammary gland alveoli

Answer 17

placental lactogen / chorionic somatotropin

Question 18

Function of what hormone?

1. FSH-like effect - causes dev of ovarian follicles
2. used as superovulation drugs in animals

Answer 18

Equine chorionic gonadotropin (eCG) or

Pregnant mare gonadotropin (PMSG) -
old name

Question 19

Structure of secreting eCG involves trophoblasts of the placenta to form
______ ___

Answer 19

endometrial cups

Question 20

eCG secretion in pregnant MARES

Answer 20

~40 days of pregnancy

Question 21

peak eCG secretion in pregnant MARES

Answer 21

~60 days

Question 22

when eCG secretion is non-detectable in MARES

Answer 22

140-160 days

Question 23

Factors affecting the length of gestation:

when a younger heifer birth earlier than older heifers

Answer 23

maternal factor

Question 24

Factors affecting the length of gestation:

• litter size = the larger litter the earlier the parturition
• sex of fetus (cow, mare) = longer gestation when fetus is a male

Answer 24

fetal factors

Question 25

Factors affecting the length of gestation:

• Holstein: 292 days pregnancy
• Ayrshire: 278 days

Answer 25

genetic factors (species/breed)

Question 26

Factors affecting the length of gestation: