Maternal Recognition of Pregnancy - Anatomy & Physiology
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Overview
| Species | Cow | Ewe | Sow | Mare | Queen | Bitch | |
|---|---|---|---|---|---|---|---|
| Preganacy Recognition Factor | Bovine Interferon tau | Ovine Interferon tau | Oestrogen and Pituitary Prolactin | Unidentified | Pituitary Prolactin | None Required |
Ruminants
- The free-floating blastocyst produces specific proteins that signal to prevent luteolysis.
- Sheep blastocysts produce ovine interferon tau (OIFN-τ)
- Cattle blastocysts produce bovine interferon tau (BIFN-τ)
- 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.