Quantitative immunogold ultracryomicrotome studies of the distribution of periimplantation proteins in the sheep.
Several mammalian uterine and conceptus proteins are produced at specific stages of implantation. Ovine trophoblast protein-1 (OTP-1) is only synthesised in vitro by conceptus tissue from between 13 and 21 days of pregnancy (dpc). This immunogold ultracryosection study shows that, during this period, OTP-1 immunoreactivity is only found in the Golgi body of the trophectodermal cells. A second protein, of 14 kD molecular weight (14 K protein), has a more varied distribution being found in membrane-bounded crystals in uterine epithelium and trophectodermal cells, and distributed throughout the cytosol and nucleoplasm of the uterine epithelium. There are only trace amounts of the 14 K protein in the fetomaternal syncytium which replaces the uterine epithelium during implantation, and no crystals are found in the trophectoderm after cotyledonary villus formation is initiated at 24-25 dpc. The crystals containing 14 K protein persist throughout pregnancy in the intercotyledonary areas. The narrow time window of OTP-1 occurrence reinforces the suggestion that this represents an important developmental signal, whereas the distribution of the 14 K protein indicates a more general nutritive function.
Wooding
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AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK.
Morgan
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Roberts
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D000818:Animals; D015925:Cryopreservation / Q000379:methods; D047108:Embryonic Development; D005260:Female; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D007150:Immunohistochemistry / Q000379:methods; D007370:Interferon Type I; D008186:Luteolytic Agents / Q000037:antagonists & inhibitors*; D008854:Microscopy, Electron / Q000379:methods; D008867:Microtomy / Q000379:methods; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000032:analysis / Q000378:metabolism*; D012756:Sheep; D014327:Trophoblasts / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure
D007370:Interferon Type I; D008186:Luteolytic Agents; D011257:Pregnancy Proteins; C020947:interferon tau