placentation Flashcards
what is intrauterine competition? what is an example?
multiple embryos will implant, only a few will survive.
EX. pronghorn antelope
what is placental implantation
-intimate contact of developing embryo with uterine mucosa
-initial sticky attachment between placenta and embryo(immobilization)
what type of placental attachment is most evolved
diffuse/less invasive types
species variations of placental implantation
-position of implantation site
-invasiveness
-area of contact
-time of implantation(delayed)
histotroph nutrition
-stored energy
-mRNA already in cytoplasm
-secreted by uterine glands
what is necessary for pre-attachment development
-histotroph nutrition
-embryo and uterine communication
syncytial
TCGs invade and engulf luminal epithelium to form syncytial layer
what secretes PAGs
Trophoblast giant cells
what do trophoblast giant cells form from
differentiate from mononuclear trophoblast cells
what is efficiency of transfer across placenta dependent on
uterine and placental size
what is selectively transported across the placenta
-amino acids, fatty acids, glucose
-CO2, O2
-Vitamins, minerals, electrolytes
functions of the placenta
-nutrient transfer from dam to fetus
-transmission of waste products from fetus to dam
-protection from shock
-hormone production
number of layers between fetal and maternal tissue for epitheliochorial placentas
approximately 6
number of layers between fetal and maternal tissue for hemochorial placentas
3
number of layers between fetal and maternal tissue for endotheliochorial placentas
5
T/F pig placenta interacts with the endometrium through interdigitation
FALSE. its through folding
what structure is unique to horse placentas that allows it to interact with the endometrium
microcotyledons
what are microcotyledons
high amount of placental folding in specific areas
T/F placentomes get tighter as pregnancy progresses
TRUE
why is it hard to use crown to rump design to estimate fetal age during early pregnancy
fetus is often folded in early pregnancy and unfolds as it grows
factors affecting fetal growth
-genetics
-environment
-nutrition
-litter size
how does the environment affect fetal growth
placental and uterine size
how does nutrition affect fetal growth
smoking
diet
factors affecting gestation length
-fetal sex
-litter size
-age of dam
-genetics
-season
which sex generally has longer gestation length
male(1-2 days longer)
T/F twins have shorter gestation than singles
TRUE(5-10 days less)
T/F older dams have longer pregnancies
TRUE(1-2 days longer)
length of gestatiopn
-cow
-ewe
-doe
-sow
-mare
-human
-mice
-elephant
cow:9 months
ewe/doe:5 months
sow:3 mo, 3 wks, 3 days
mare:11 months
human: 9 months
mice: 21 days
elephant: 2 years
