Changes

* Lies mostly behind the ischial arch, sloping ventrally to its opening at the vulva.

* Lies mostly behind the ischial arch, sloping ventrally to its opening at the vulva.

* The wall contains vestibular glands.   

* The wall contains vestibular glands.   

** Secretions from these glands keeps the mucosa of the vestibule moist and facilitates [[Copulatory Behaviour - Anatomy & Physiology|coitus]] and [[Reproductive_System_- Anatomy & Physiology#Parturition|parturition]].

** Secretions from these glands keeps the mucosa of the vestibule moist and facilitates [[Copulatory Behaviour - Anatomy & Physiology|coitus]] and [[Normal Parturition - Anatomy & Physiology|parturition]].

** At [[Oestrus Behaviour - Anatomy & Physiology|oestrus]], the odour of these secretions sexually stimulates the male.

** At [[Oestrus Behaviour - Anatomy & Physiology|oestrus]], the odour of these secretions sexually stimulates the male.

* The wall consists of:

* The wall consists of:

** Mucosal layer lined by stratified squamous epithelium

** Mucosal layer lined by stratified squamous epithelium

** Layer of [[Muscles_- Anatomy & Physiology#Smooth_Muscle|smooth muscle]]

** Layer of [[Muscles - Anatomy & Physiology#Smooth_Muscle|smooth muscle]]

*** Inner circular and outer longitudinal layers

*** Inner circular and outer longitudinal layers

** Outer layer of adventitia

** Outer layer of adventitia

** Not lined by Mesothelium

** Not lined by Mesothelium

*** Merges with the adventitial layers of the [[Urinary_Bladder_- Anatomy & Physiology|bladder]] anteriorly and [[Rectum_- Anatomy & Physiology|rectum]] posteriorly.

*** Merges with the adventitial layers of the [[Urinary_Bladder_- Anatomy & Physiology|bladder]] anteriorly and [[Rectum_- Anatomy & Physiology|rectum]] posteriorly.

* This combination of elastic fibres and [[Muscles_- Anatomy & Physiology#Smooth_Muscle|muscular]] layers allows the massive distension that occurs during [[Reproductive_System_- Anatomy & Physiology#Parturition|parturition]].

* This combination of elastic fibres and [[Muscles_- Anatomy & Physiology#Smooth_Muscle|muscular]] layers allows the massive distension that occurs during [[Normal Parturition - Anatomy & Physiology|parturition]].

* After [[Copulatory Behaviour - Anatomy & Physiology|coitus]], contraction of the smooth muscle layer ensures that the pool of semen remains within the cervical region.

* After [[Copulatory Behaviour - Anatomy & Physiology|coitus]], contraction of the smooth muscle layer ensures that the pool of semen remains within the cervical region.

* When relaxed, the vaginal wall collapses to obliterate the lumen and the vaginal epithelium is thrown into folds.

* When relaxed, the vaginal wall collapses to obliterate the lumen and the vaginal epithelium is thrown into folds.