Difference between revisions of "Maternal Recognition of Pregnancy - Anatomy & Physiology"
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* As a result, there is no production of the luteolytic factor PGF2α and the corpus luteum is maintained. | * 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. | * The corpus luteum then produces progesterone to maintain the pregnancy. | ||
+ | |||
+ | === The Conceptus === | ||
+ | |||
+ | * The ruminant conceptus undergoes rapid elongation between day 14 and 16. | ||
+ | * During this period, IFN-τ is secreted at high levels before decreaseing. | ||
+ | * Small embryos produce much less IFN-τ than larger embryos. | ||
+ | * There is a hige proportion of embryo loss in the first 3 weeks of gestation, as small embryos fail to secrete enough IFN-τ in this critical period. Thus they do not block luteolysis. | ||
+ | ** This may be related to poor nutritional status of the mother. |
Revision as of 21:36, 13 September 2008
|
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.
The Conceptus
- The ruminant conceptus undergoes rapid elongation between day 14 and 16.
- During this period, IFN-τ is secreted at high levels before decreaseing.
- Small embryos produce much less IFN-τ than larger embryos.
- There is a hige proportion of embryo loss in the first 3 weeks of gestation, as small embryos fail to secrete enough IFN-τ in this critical period. Thus they do not block luteolysis.
- This may be related to poor nutritional status of the mother.