Pregnancy and placentation (Describe the maternal recognition of pregnancy…
Pregnancy and placentation
Describe the maternal recognition of pregnancy in the major domestic species
Blastocysts hatch from here
Progesterone secreted by placenta, but until fully developed = Corpus luteum
- BLOCKS oxytosin receptors, so no PGF and hense signal stopped.
CL of cats and dogs - last as long as pregnancy in dogs and oestrous in cats
Luteolysis (Breaking down CL)
Prostaglandin F12 (PGF)
ENDOMENTRUM released - BUT PGF has short half life, so needs adaptation... countercurrent mechanism. (RUMINANTS & PIGS)
Promoted by oxytosin binding to receptor - Secreted by Cl
The luteolytic signal needs to be stopped to allow pregancy ! - EXOCRINE secretion of PGF
In horses, the conceptus will migrate TO endometrial surface. Needs specific gonadotropin to prevent luteolysis
Explain how the extra-embryonic tissues form the placenta
Placenta is a double sac protecting foetus
All of foetal origin (Tissue)
Inner - Amnion from amniotic cavity
Outer - Chorioallantois
FUNCTIONAL PART OF PLACENTA? -
act as an exchange apparatus. Increase SA for exchange
Describe the form& extent of placental attachment in the main domestic species
Primates - UNIQUE. The placenta implants so there are very few layers beween placenta and maternal blood. - OPEN WOUND FOR PARTURITION SO MORE WOMEN BLEED TO DEATH
Non primate placenta attach...
More layers between blood and placenta
COTYLEDONARY placenta - Have numerous button like
DIFFUSE - Uniform distribution of choronic villi :pig: :horse:
More than primates (Haemochorial) but fewer than epitheliochorial
ZONARY - Band like zone of choronic villi :cat: :dog:
Describe the anatomy of the umbilical cord
Classified according to distribution of choronic villi on surfaces...
Function - Endocrine gland (Transient)
Hormones which Maintain pregnancy, Stim. mammary glands, foestal growth promoters
R&L umbillical artery
Umbillical vein (RUm - 2)
Describe how freemartins develop in cattle
Sexual differenciaton = SRY gene presence or not
SRY causes Testes to develop - Sertoli cells produce MIH and AMH - accessory sex glands and duct system
NO SRY - Tract = female, NO AMH, ducts become ovaries etc. :girl:
When you have TWINS, share a common blood supply.
SRY & testes develop before Ovaries, so reaches BOTH foetuses. Her repro tract does not develop properly and no ovaries. STERILE.