Maternal Recognition of Pregnancy - Anatomy & Physiology

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()Map REPRODUCTIVE SYSTEM (Map)
GESTATION




Ruminants

  • The free-floating blastocyst produces specific proteins that signal to prevent luteolysis.
  • Sheep blastocysts produce ovine interferon tau (OIFN-tau)
  • Cattle blastocysts produce bovine interferon tau (BIFN-tau)
  • Interferon tau is a small protein produced by trophoblastic cells of the blastocyst.
  • It is present in the uterus at day 13-21 after ovulation.
  • It is not luteotrophic, so does not enhance progesterone production by the corpus luteum.
  • Instead, it binds to the uterine endometrium and inhibits the synthesis of oxytocin receptors.
  • In addition to preventing the upregulation of oxytocin receptors, interferon tau binds to the apical portion of uterine glands to promote synthesis of proteins that are critical for embryonic survival pre-implantation.
  • As a result, there is no production of the luteolytic factor PGF2α and the corpus luteum is maintained.
  • The corpus luteum then produces progesterone to maintain the pregnancy.