Maternal Recognition of Pregnancy Flashcards
Conceptus definition
An embryo or fetus with all its membranes and accessory structures
Embryo, conceptus, and fetus are terms often used interchangeably
Fetus definition
An embryo that has completed organogenesis – recognizable as a member of its species
Embryo, conceptus, and fetus are terms often used interchangeably
Establishment of pregnancy requires what 4 things?
Fertilization
Early embryonic development
Maternal recognition of pregnancy
Placentation
Sequence of fertilization to attachment
Sperm fertilizes the oocyte in the oviduct
Conceptus formation and starts to descend to the uterus
Becomes blastocyst in the uterus
Blastocyst hatches and migrates in the uterus
Embryonic membrane formation
Maternal recognition of pregnancy occurs
Placentation/attachment to the endometrium
Embryo “hatching” occurs __-__ days post ovulation
6-8
_______ _______ is essential for nutrient exchange, placental attachment and maternal recognition of pregnancy
Uterine epithelium
In the cow and the ewe, the embryo must be on the same side as…
The CL (ipsilateral)
In the Mare the embryo must migrate between…
The 2 uterine horns until day 16
Continues to grow
Has NO relationship to CL
Uterine migration and equidistant spacing between embryos is essential to embryonic survival in….
Litter bearing species
Trophoblast elongation is on Day 11 or 12 in the pig or starts around Day ____ in ruminants
12
Maternal Recognition of pregnancy prevents…
Luteolysis
Early on the embryo will attach to the ________…
Endometrium by extra-embryonic membranes
Organogenesis is the most..
Susceptible period of the pregnancy
1st trimester
After attachment of embryo it will undergo placentation and…
Fetal growth occurs
-Sexual differentiation
-System maturation
-Specialized cell development (CNS, hair)
Ends in parturition
Gestation length in cows
~9m (278-293d)
Gestation length in mares
~11m (330-345d)
Gestation length in ewes
~5m (144-151)
Gestation length in the sow
3m, 3w, 3d (112-115d)
Gestation length in the Bitch
65d
(~2m)
Gestation length in the queen
58-70d
(~2m)
Maternal Recognition happens prior to the release of ______ to prevent ________ if embryo present
PGF2a
prevent luteolysis
Maternal Recognition signal comes from…
The embryo
May be hormone and/or protein
Cow MRP
Conceptus enters uterus at ~day 5– 6
Embryo elongation by Day 13
Maternal recognition of pregnancy:
Day 15 - 18
-bovine interferon INF- tau)
-bovine trophoblastic protein 1 (bTP-1)
Mare MRP
Conceptus enters the uterus Day 5 –6
-Amnionic vesicle (AV) remains spherical and diameter increases rapidly
Maternal recognition of pregnancy
-Increase embryo mobility/uterine; contractions on Days 11-16
***NO hormonal signal identified
Embryonic motility plays an IMPORTANT role
Embryo motility is lost at Day 16 when it becomes fixed
Embryonic motility plays an important role of MRP in which species?
Mare
Last at day 16 when attachment occurs
Ewe MRP
Conceptus enters the uterus by Day 5
Maternal recognition of pregnancy:
Day 12-14
Ovine interferon - oINF-tau (oTP-1)
Sow MRP
Conceptus enters the uterus by Day 3 as a 4-cell
Maternal recognition of pregnancy
Day 11 – 12
Signal is ESTRADIOL by conceptus
-Causes intraluminal vs. intravenous passage of endometrial PGF2a
-FOUR EMBRYOS must be present for pregnancy to be maintained- 2 in each horn
In the sow at least _______ embryos must be present for pregnancy to be maintained
Four (2 in each horn)
Bitch/Queen MRP
Conceptus enters the uterus
-Bitch - Day 9 – 11
-Queen – Day 4 – 5
Maternal recognition of pregnancy
UNKNOWN
Similar hormonal environment of the non- pregnant bitch/queen
-Prolonged CL lifespan
Endocrinology of Pregnancy- Progesterone
Extended production
Ovarian (early) and placental (mid to late) origins
Luteal-dependent species maintain ovarian production throughout pregnancy
Functions:
myometrial gland proliferation
uterine quiescence - myometrial inhibition
mammary development
Function of progesterone during pregnancy
myometrial gland proliferation
uterine quiescence - myometrial inhibition
mammary development
Endocrinology of pregnancy- Estrogens
Ovarian, placental and/or fetal origin
Gradual increase with peak around the time of parturition
Primer for:
oxytocin - myometrial receptors
progesterone, prolactin - mammary development
In pregnancy Estrogens may originate from….
Ovarian, placental and/or fetus
Estrogens during pregnancy prime for…
oxytocin - myometrial receptors
progesterone, prolactin - mammary development
Endocrinology of Pregnancy- gonadotropins
Hypothalamic source-
Low levels of LH during pregnancy
FSH waves may continue
Progesterone negative feedback on the hypothalamus
LH is luteotropic early
Placental source (mare)- Equine Chorionic Gonadotropin (eCG) (previously PMSG) – from “endometrial cups”
LH-like effects (FSH-like activity in other species)
In mares eCG is produced by….
Endometrial cups during pregnancy
In Mares eCG (equine Chorionic Gonadotropin) acts like….
LH
In other species- FSH like
In other species (not mare), eCG (equine Chorionic Gonadotropin) has activity that mimics…
FSH
Luteal-Independent species
only needs the CL of ovulation for the first part of pregnancy followed by placental production
Cow
Ewe
Mare
Luteal-Dependent species
needs the CL of ovulation for the entire duration of pregnancy
Sow
Doe
Bitch
Queen
Terminology used to describe pregnancy
Polytocous – litter bearing
Monotocous – single offspring
Nulliparous – never carried a pregnancy
Primaparous – first pregnancy
Multiparous – multiple pregnancies
