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Pregnancy and Parturition - Horse Anatomy (view source)
Revision as of 17:47, 26 November 2012
, 17:47, 26 November 2012→Parturition
==Parturition==
==Parturition==
The step in the reproductive process that immediately precedes lactation, uterine involution and return to cyclicity. It is initiated by the foetus and involves a complex cascade of endocrine events. Parturition is the process by which the conceptus (foetus, placenta and placental membranes) is expelled from the [[Uterus - Anatomy & Physiology|uterus]]; this requires [[Cervical Softening - Anatomy & Physiology|cervical softening]],[[Uterine Contraction - Anatomy & Physiology|coordinated myometrial contractions]] and contraction of abdominal muscles
to occur.
===Stages of Parturition===
===Stages of Parturition===
*Stage 1: This is the preparatory stage, starting at the onset of regular uterine contractions followed by cervical dilatation and the foetus assuming the correct disposition for passage through the birth canal. This takes 1-4 hours.
*Stage 1: This is the preparatory stage, starting at the onset of regular uterine contractions followed by cervical dilatation and the foetus assuming the correct disposition for passage through the birth canal. This takes 1-4 hours.
*Stage 2: The expulsive stage, characterised by the onset of abdominal contractions which together with uterine contractions lead to foetal expulsion. This takes 12-30 minutes.
*Stage 2: The expulsive stage, characterised by the onset of abdominal contractions which together with uterine contractions lead to foetal expulsion. This takes 12-30 minutes.
*Stage 3: Separation and expulsion of the foetal membranes. This takes 1 hour.
*Stage 3: Separation and expulsion of the foetal membranes. This takes 1 hour.