Implantation, Pregnancy, Placenta, and Parturition Flashcards
What are the four steps of embryonic preparation between syngamy and implantation?
development of the embryo, hatching, post-hatching embryogenesis, and prevention of luteolysis
In post-hatching embryogenesis, where is the amnion formed?
on the implantation pole
In post-hatching embryogenesis, where is the chorioallantoic membrane formed?
on the distal pole of the embryo
How do ruminants and swine embryos differentially signal the uterus that implantation is imminents and how the signaling influences the ovary?
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.
What is the role of CG in maintaining the early part of pregnancy?
CG is a LH-like hormone released from implanted trophoblasts and this hormone maintaines progesterone release from the CL
What is the importance of accessory CL in the maintenance of early to mid-pregnancy?
accessory CLs are formed to assist in progesterone release as the primary CL undergoes its inevitable involution
What is the hormonal importance of the placenta in the maintenance of mid-pregnancy and beyond?
in some species the placenta assumes the responsibility of producing most of the progesterone needed for the maintenance of pregnancy
What is the function of eCG in the mare?
it activates the LH receptor on SLCs in the CL and promotes the growth of accessory CLs
What is the function of eCG in species other than the mare?
FSH-like activity and is used for superovulation in embryo transfer
What is placental lactogen?
a chorionic somatammotropin in the placenta
What is the function of placental lactogen?
it mobilizes maternal nutrients to the fetus and stimulates the growth and development of the mammary gland
During parturition, what hormones does the placenta produce?
relaxin and oxytocin
In the bovine, what produces relaxin instead of the placenta?
the corpus luteum
How is fetal cortisol involved in parturition?
its rises which leads to many of the maternal hormonal changes that cumulate in parturition
What is the primary feedback hormone during parturition?
oxytocin
What is the role of oxytocin during parturition?
it causes myometrial contractions that stimulate further release of oxytocin
What is the role of oxytocin after parturition?
it is continually produced to expel the placenta, reduce the size of the post-partum uterus, and expel bacteria and other unwanted debris
What stimulates oxytocin release post partum?
suckling calf and mechanical milking
What are the endocrine functions of the placenta?
stimulator of ovarian function, maintains pregnancy, influences fetal growth and development, stimulates the mammary gland, and assists in parturition
What are the classification schemes of the placenta?
degree of contact, intamacy of contact, and fate of placenta
What are the different types of ‘degree of contact’ of the placenta?
diffuse, cotyledonary, zonary, and discoid
What is intamacy of contact dictated by?
the number of layers between maternal and fetal blood supplies
What are the different types of intamacy of contact?
epitheliochorial, syndesmochorial, endotheliochorial, and hemochorial
What are the two fates of the placenta?
deciduous and non-deciduous
What is the ‘deciduous’ fate of the placenta?
all of the placenta falls out of the uterus after parturition
What is the ‘non-deciduous’ fate of the placenta?
a portion of the placenta stays in the uterus after parturition
What types of molecules can cross the B-P-B via simple diffusion?
water, gasses such as O2, CO2, and CO, and lipid hormones
What types of molecules can cross the B-P-B via facilitated diffusion?
glucose, amino acids, and immunoglobulins
What types of molecules can cross the B-P-B via active transport?
sodium and potassium
