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Placentation, Gestation, & Parturition - Coggle Diagram

- - - - discoid
        
        form a regionalized disc of chorionic villi that interface with endometrium
        
        rodents & primates
      - cotyledonary
        
        cotyledons: numerous, discrete, button-like structures
        
        ruminants
        
        fetal & maternal cotyledons make up interface; originate in caruncles
      - diffuse
        
        uniform distribution of chorionic villi that cover surface of chorion
        
        horse
        
        microcotyledons: specialized microzones of chorionic villi
        
        endometrial cups
        
        equine chorionic gonadotropin (eCG)
        
        pig
      - zonary
        
        band-like zone of chorionic villi; paraplacenta: pigmented ring at either end of central zone
        
        dogs & cats
    - - epitheliochorial: 6 layers
        
        mare
        
        sow
        
        ruminants
        
        syndesmochorial placenta: endometrial epithelium erodes & regrows; intermittent exposure of maternal capillaries to chorionic epithelium
        
        binucleate giant cells: unique to ruminant placenta
        
        secrete
        
        placental lactogen
        
        pregnancy specific protein B aka pregnancy associated glycoproteins (PAG)
        
        only found in ruminants
      - endotheliochorial: 5 layers
        
        absence of endometrial epithelium & underlying interstitium
        
        dogs & cats
      - hemochorial: 3 layers
        
        chorionic epithelium in close contact with maternal blood
        
        primates & rodents
  - - - glucose, triglycerides, steroids, thyroid hormone, catecholamines, amino acids, water-soluble vitamins
      - toxins & meds
        
        ethyl alcohol, lead, phosphorous, mercury, opiates, barbiturates, antibiotics
        
        teratogens: cause birth defects
        
        LSD, amphetamines, lithium, diethylstilbestrol, thalidomide
      - some viruses & bacteria
    - - TSH, GH, ACTH, insulin, glucagon, fat-soluble vitamins
  - - - eCG
        
        begin secretion at time of attachment
        
        maintenance of primary CL
        
        increased progesterone
        
        causes ovulation
        
        formation & maintenance of supplementary CL
        
        increased progesterone
        
        does not have FSH-like actions in mare, but does when given to other spp
      - pregnant mare's serum gonadotropin (PMSG)
    - - hCG
        
        similar to eCG except it starts to be secreted when blastocyst hatches; no supplemental CL
    - - blocks myometrial contractions
      - ewe, mare, human
        
        CL becomes unneeded
      - sow & rabbit
        
        CL needed for all of pregnancy or it will terminate
      - cow
        
        CL needed for first 8 months of pregnancy or it will terminate
    - - signals early preparturient period
    - - rats, mice, sheep, cows, humans
      - stimulates mammary glands
      - promotes growth of fetus
    - - loosens pelvic ligaments
      - mares, cats, dogs, pigs, rabbits, some primates
- - - - stage 3: expulsion of fetal membranes
        
        caused by vasoconstriction of arteries in chorionic villi; must also occur on maternal side in hemochorial placentation so hemorrhage does not occur
        
        required myometrial contractions
        
        ruminants sometimes retain placenta
      - as fetus enters birth canal, it becomes hypoxic
        
        promotes fetal mvmt
        
        promotes further myometrial contractions
      - dystocia usually occurs in this stage
        
        excessive size of fetus
        
        failure of proper fetal rotation
        
        multiple births in spp that usually have only one offspring at a time (monotocous)
        
        both twins presented simultaneously
        
        first fetus positioned abnormally & blocks second fetus
        
        uterus becomes fatigued
    - - releases ACTH
        
        fetal adrenocorticoids released
        
        cascade of endocrine changes in mother
        
        fetal cortisol promotes synthesis of enzymes that convert progesterone to estradiol; fetal cortisol also causes placental synthesis of PGF2-alpha
        
        removal of "progesterone" block; increased estrogen
        
        myometrial contractions
        
        1 more item...
        
        PGF2-alpha stimulates relaxin secretion by either CL or placenta, depending on species
        
        loosens CT of pelvic ligs & cervix
        
        increased repro tract secretions, esp by cervix
        
        dilation of cervix