Parturition

Question 1

What changes occur in the female reproductive tract during parturition?

Answer 1

-dilation of the cervix
-relaxation of the pubic symphysis (connective tissue of the pubic area)
-uterine contractions

Question 2

How does dilation of the cervix occur? relaxation of the pubic symphysis?

Answer 2

the combined effect between E2 and relaxin (for both processes)

Question 3

What contributes to uterine contractions? (3)

Answer 3

-P4 is removed (inhibitor)
-PGF2a causes initial contractions
-E2 increases oxytocin receptors and increased oxytocin promotes further contractions

Question 4

Produced by the CL- is stored, then dumped
restructures cervix to allow for dilation

Answer 4

Relaxin

Question 5

What stimulates the development of the duct system in the mammary glands throughout gestation?

Answer 5

E2

Question 6

What stimulates alveolar growth throughout gestation?

Answer 6

P4

Question 7

What two hormones inhibit milk production?
their removal allows for lactogenesis

Answer 7

E2 & P4

Question 8

What changes to the fetus occur prior to parturition? (4)

Answer 8

-maturation of lungs (aquatic to terrestrial)
-thermoregulation
-nutrient absorption
-immune function

Question 9

How does the fetus initiate parturition?

Answer 9

-hypothalamus matures and produces CRH
-AP produces ACTH (fetus stresses out)
-fetal placenta shifts from P4 to E2 production

Question 10

How does the dam initiate parturition?

Answer 10

-uterus produces PGF2a
-CL loses P4 and releases relaxin
-PP releases oxytocin -> uterine contractions

Question 11

Who has control over when parturition happens (given no outside influence/manipulation)

Answer 11

the fetus

Question 12

What are some signs of impending parturition?

Answer 12

• udder development & presence of milk
• hollowing and relaxation (increased respiration)
• nesting
• isolation
• off feed
• colicky/discomfort

Question 13

What are the 3 stages of parturition?

Answer 13

• preparatory
• fetal expulsion
• delivery of the membranes

Question 14

What 4 things happen during the preparatory stage of parturition?

Answer 14

• uterine contractions (irregular to regular)
• rotation of the fetus
• dilation of the cervix
• relaxation of the pubic symphysis

Question 15

What 5 things happen during the fetal expulsion stage?

Answer 15

• chorioallantois ruptures (water breaks)
• fetus is forced through the birth canal
• rupturing of amnion
• delivery of the fetus
• umbilical cord is severed

Question 16

What happens during the delivery of the membranes stage? What is there a risk of?

Answer 16

• chorionic villi loosen and detach
• afterbirth is shed
• there’s a risk for retained placentas, especially in ruminants

Question 17

Except for the mare, ______________________ are the major source of estrogens found in the mother during pregnancy.

Answer 17

Placental membranes

Question 18

Parturition is induced in the ewe by

Answer 18

dexamethasone