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Female (1) (Fertilization (Oocyte Reactions (in meiotic arrest until…

- - - - Allows Exchange between maternal and foetal circulations
      - Implications
        
        Ease of transfer of immunoglobulins, drugs etc (E.g. horses- Diffuse, if different blood types foal dies when drinks colostrum)
        
        Indications of premature placental separation (horses whole uterus involved, cattle- cotyledonary, only patches)
        
        Likelihood of RFM
  - - - Embryo/uterus releases substances that blocks PGF prod=
        blocking luteolysis
      - Ruminants= embryo prod trophoblastin= stops PGF synthesis
      - Pigs= Embryo prod oestrogens= redirection of PGF into uterine lumen not v.
      - Horse=: moves around day 9-15= releases oestrogens= blocks PGF
- - - - maintainence= need high PROG
      - Conceptus plays active role in maintaining preg.
      - PGF2alpha induces luteolysis- need to Px
      - cow and ewe
        
        Blastocyst produce Trophoblastin: Interferon
      - Mare
        
        spherical conceptus moves around until 9-15d= release oestrogens= block PGF2alpha prod.
        
        aka "Transuterine migration."
      - Pigs
        
        Conceptus prod Oestrogens= redirection of PGF2alpha into lumen instead of vein.
        
        Need atleast 4 embryos, in both horns by 10-12d
      - Bitch and Queen
        
        dont req signal= Lifespan of CL= gestation period
    - - Earliest inducator- pre-implantation period
      - Immunomodulator- conceptus ensures its own defense against immunological rejection
    - - Maintains preg- negative feedback on hypoth. (stops cycle)
      - How= decreases uterine motility= increases glandular secretion of uterus (uterine milk for nutrition until attachment)
      - Sources: CL and placenta (spp variation)
        
        Bovine: CL, placenta at 6-8mnths
        
        Ovine: CL then placenta +/- 50d
        
        Canine, porcine, caprine, camelid: CL ENTIRE gestation
        
        Feline: CL and placenta
        
        Equine: CL until 45d, supplementary CL 40-90d, placenta >60d
    - - From: AP
      - Luteolytic in some sp (supports CL)
      - Function: mammary development, lactogenesis
    - - Polypeptide hormone
      - who: rats, mice, sheep, cows, humans
      - Function
        
        Somatotrophic: promoting growth
        
        Lactogenic: stimulation of mammary gland
    - - Source: Placents
      - humans: hCG
        Mares: eCG from endometrial cups
      - Can be protected on early preg test
      - Function= increase number of CL and secretion of prog.
    - - Endometrial cups: invade into uterus= make eCG= increase Prog
      - Extracorpolutea: makes extra Prog
      - Timeline
        
        35-120d= foetal trophoblastic cells invading endometrium
        
        37-150d= produce eCG
        
        40-120d= test eCG
      - Prog: ovulated, prog from CL, drops blow 0 before 21 days), stays
        
        eCG: startin day 37 ish, increases then drops away
        
        get extracorpolutear on ovaries producing progesterone
        
        Then prog from Placenta takes over and increases until birth.
        
        Oestrogen from ovaries, Oestrogen from placenta (from converting progesterone, and from foetus). Oestrogen increases during partuition at the end.
    - - Source: primates and equine= fetus produces androgens, prog.
        converted to enxymes in placenta
      - Can use as preg test
      - Equine: lots formed by extracorpolutea (excreted in ur.)
  - - - corticotrophin release hormone from hypothalamus
      - ACTH from AP
      - Rise in Foetal Cortisol from adrenals= near time of parturition.
      - Brain produces oxytocin when pushing on cervix.
    - - Oestrogens + uterine stretch
        
        expression of ptoeins allowing uterus to contract
      - Ion channels, Oxytocin and PG receptors, connexin (forms GAP junctions between cells)
      - NOW have uterus that can bind tonic hormones and coordinate contractions
    - - Stimulate prod and release of Uterine PG
      - Up=regulate expression of receptors for tonic hormones= increases responsiveness to oxytocin and PG
      - Alters structure of collagen fibres in cervix= softens
    - - PG luteolysis= less Prog= down regulation of prog receptors
      - Oxytocin and PG= increase intracellular Ca= activate actin-myosin interactions and m. cell shortening
        Stretching of cervix= further oxytocin release
    - - PGE= cervical relaxation
      - Relaxin (CL/placental)= connective tissue change= cervix and pelvic lig relax
    - - Sheep
        
        Prog decreases= oxytocin increases= prolactin increases (due to prog drop)
      - Mare
        
        prog rise in last mnth, fall one day after= oestrogen falls towards end
        
        Oxytocin and PGF2alpha= myometrial contractions
      - D and C
        
        Cortisol= PGF release= luteolysis
        
        Decreased prog in last wk
      - PGF2alpha= regression of CL, myometrial contractions.
      - PGF2alpha and PGE= cervical relaxation
      - PGE= closure of ductus arteriosus
  - - - active contractions of myometrium
      - Dilation of cervix
      - Foetus may be rotating into position
      - Restless, uncomfortable
    - - BABY COMES OUT
      - Foetus enters birth canal
      - Placenta (allantois) ruptures
      - Abdominal straining= foetus through cervix stimulates
    - - Expulsion of foetal membranes
      - some animals eat (ruminal dysfunction)
      - Involution of uterus- contracts and regresses to normal size
      - Normal lochia discharged for 1-3 wks
- - - - 2-3 waves (with GnRH waves)
        Make follicle respond= need receptors
        Inhibit other follicles through local feedback
    - - Follicle grow and produce
        +ve feedback on hypothalamus= FSH and LH from ant. pituitary
    - - Spike responding to oestrogen= OVULATION
        req for follicles to grow (during middle of cycle after follicle starts to grow)
    - - From CL
        negative feedback on brain= stopping GnRH
        3/4 through cycle= pregnant= prog, IF NOT= PG released, CL gone, prog stops= luteolysis...