Implantation, Pregnancy, Placenta, and Parturition

Question 1

What are the four steps of embryonic preparation between syngamy and implantation?

Answer 1

development of the embryo, hatching, post-hatching embryogenesis, and prevention of luteolysis

Question 2

In post-hatching embryogenesis, where is the amnion formed?

Answer 2

on the implantation pole

Question 3

In post-hatching embryogenesis, where is the chorioallantoic membrane formed?

Answer 3

on the distal pole of the embryo

Question 4

How do ruminants and swine embryos differentially signal the uterus that implantation is imminents and how the signaling influences the ovary?

Answer 4

Ruminant embryos release IFN-t that decreases oxytocin receptors, thus preventing the release of luteolytic hormone PGF2 alpha. Swine embryos release estrogen that re-routes PGF2 alpha to the uterine lumen where it is destroyed, thus preventing ovarian luteolysis.

Question 5

What is the role of CG in maintaining the early part of pregnancy?

Answer 5

CG is a LH-like hormone released from implanted trophoblasts and this hormone maintaines progesterone release from the CL

Question 6

What is the importance of accessory CL in the maintenance of early to mid-pregnancy?

Answer 6

accessory CLs are formed to assist in progesterone release as the primary CL undergoes its inevitable involution

Question 7

What is the hormonal importance of the placenta in the maintenance of mid-pregnancy and beyond?

Answer 7

in some species the placenta assumes the responsibility of producing most of the progesterone needed for the maintenance of pregnancy

Question 8

What is the function of eCG in the mare?

Answer 8

it activates the LH receptor on SLCs in the CL and promotes the growth of accessory CLs

Question 9

What is the function of eCG in species other than the mare?

Answer 9

FSH-like activity and is used for superovulation in embryo transfer

Question 10

What is placental lactogen?

Answer 10

a chorionic somatammotropin in the placenta

Question 11

What is the function of placental lactogen?

Answer 11

it mobilizes maternal nutrients to the fetus and stimulates the growth and development of the mammary gland

Question 12

During parturition, what hormones does the placenta produce?

Answer 12

relaxin and oxytocin

Question 13

In the bovine, what produces relaxin instead of the placenta?

Answer 13

the corpus luteum

Question 14

How is fetal cortisol involved in parturition?

Answer 14

its rises which leads to many of the maternal hormonal changes that cumulate in parturition

Question 15

What is the primary feedback hormone during parturition?

Answer 15

oxytocin

Question 16

What is the role of oxytocin during parturition?

Answer 16

it causes myometrial contractions that stimulate further release of oxytocin

Question 17

What is the role of oxytocin after parturition?

Answer 17

it is continually produced to expel the placenta, reduce the size of the post-partum uterus, and expel bacteria and other unwanted debris

Question 18

What stimulates oxytocin release post partum?

Answer 18

suckling calf and mechanical milking

Question 19

What are the endocrine functions of the placenta?

Answer 19

stimulator of ovarian function, maintains pregnancy, influences fetal growth and development, stimulates the mammary gland, and assists in parturition

Question 20

What are the classification schemes of the placenta?

Answer 20

degree of contact, intamacy of contact, and fate of placenta

Question 21

What are the different types of ‘degree of contact’ of the placenta?

Answer 21

diffuse, cotyledonary, zonary, and discoid

Question 22

What is intamacy of contact dictated by?

Answer 22

the number of layers between maternal and fetal blood supplies

Question 23

What are the different types of intamacy of contact?

Answer 23

epitheliochorial, syndesmochorial, endotheliochorial, and hemochorial

Question 24

What are the two fates of the placenta?

Answer 24

deciduous and non-deciduous

Question 25

What is the ‘deciduous’ fate of the placenta?

Answer 25

all of the placenta falls out of the uterus after parturition

Question 26

What is the ‘non-deciduous’ fate of the placenta?

Answer 26

a portion of the placenta stays in the uterus after parturition

Question 27

What types of molecules can cross the B-P-B via simple diffusion?

Answer 27

water, gasses such as O2, CO2, and CO, and lipid hormones

Question 28

What types of molecules can cross the B-P-B via facilitated diffusion?

Answer 28

glucose, amino acids, and immunoglobulins

Question 29

What types of molecules can cross the B-P-B via active transport?

Answer 29

sodium and potassium