Lecture 19-20 Flashcards
(44 cards)
Diffuse Placenta
Horses and Pigs
Cotyledonary
Ruminants (cattle, goats, sheep, deer)
Zonary
Carnivores (dogs, cats, ferret)
Discoid
Humans, apes, monkeys, rodents
Epitheliochorial
pigs, horse, ruminants
least intimate exchange
young born leaner, lower nutrients, and less immunity
endotheliochorial
dogs, cats
hemochorial
humans,rodents
Most intimate exhange between mom and fetus
young have higher fat and nutrient stores
more developed immune system
Ruminant epitheliochorial
Syndesmochorial: the endometrial epithelium transiently erodes and then regrows so maternal connective tissues are intermittently exposed to the chorionic epithelium
Made up of Bi-nucleate cells
Binucleate Giant Cells
–migrate from chorionic to endomet. epithelium
–transfer complex mlcls from fetus to mom
–endocrine fxn (secretes lactogen, steroid and PAG’s)
–constitutes 20% of fetal placenta
–originated from trophoblast cells
Placental Function
The placenta is a transient organ: metabolic interchange between mother and fetus
the placenta is is the major endocrine organ of preg: produces hormones, stims mammary glands, and promotes fetal growth
Maternal-Fetal Exhange mechanisms
Simple Diffusion: High [ ] to low [ ] (gas and water)
Facilitated: membrane transport (proteins and glucose)
Active Transport: membrane proteins transport AGAINST gradient (Na, K, and Ca ++)
Can Cross and Can’t
pg 8 and 9 of Lec. 19
Placental Hormones Can . .
Stim Ovarian Fxn
Maintain Pregnancy
Influence Fetal Growth
Stim Mammary Function
Assist in Parturition
Progesterone
CL produces most P4 at first and then placenta
CL: secretion of endometrial glands and embryonic membrane attachment
Placenta: maintains preg
depends on species if this takes over
Progesterone Block
High P4 blocks myometrial contractions
ecg = PMSG
produced by endometrial cups of placenta
5-10 develop over placental surface
develop between days 35-60 and slough around 100
-Maintains primary CL
-forms and maintains supplemnetary CL’s
-acts like FSH
hCG
primates
from trophoblastic cells
found in blood and urine after 8-10 days of preg
pg 12 lec 19
Placental Lactogen
Somatotropic:
maternal growth hormone-like
promotes fetal growth
Lactogenic:
stims mammary gland in the dam
Somatotropic and Lactogenic balances in species
More lactogenic: ewe, woman, rat
equally: cow, goat
Relaxin
Produced by either CL or or Placenta
Causes softening of connective tissue in cervix and promotes elasticity of pelvic ligaments
Estrogen
Important close to and during birth
produced by placenta
increased estradiol removes P4 block
increase secretion of mucosa in cervix and vagina
Parturition Requires
–myometrium contractility
–cervix dilation
–fetal organ systems for putside uterus survival must be mature
–maternal organ undergone change needed for lactation
Parturition and Viviparous species
–transition of myometrium from relaxed to excited
–softening of ecm
–weakening of fetal membrane
–inflammation
Stages of Hormonal Environment
Stage 0: Uterine Contractile Quiescence
Stage 1: Initiation of uterine contraction
stage 2: expulsion of fetus
stage 3: expulsion of fetal membranes
