Changes

==The Cloaca==

==The Cloaca==

The '''[[Colon - Anatomy & Physiology|Colon]]''', '''[[Ureters - Anatomy & Physiology|ureters]]''' and '''deferent ducts'''/'''left [[Avian Female Reproductive System#Oviduct|oviduct]]''' enter at various levels. It can be divided into the '''coprodeum''', '''urodeum''' and '''proctodeum''' by complete annular folds. Some urinary excretions arriving in the cloaca become incorporated with the ingesta and move in a retrograde fashion to the [[Caecum - Anatomy & Physiology|caeca]], increasing the absorption of water and electrolytes from the urinary waste.

The '''[[Colon - Anatomy & Physiology|colon]]''', '''[[Ureters - Anatomy & Physiology|ureters]]''' and '''deferent ducts'''/'''left [[Avian Female Reproductive System#Oviduct|oviduct]]''' enter at various levels. It can be divided into the '''coprodeum''', '''urodeum''' and '''proctodeum''' by complete annular folds. Some urinary excretions arriving in the cloaca become incorporated with the ingesta and move in a retrograde fashion to the [[Caecum - Anatomy & Physiology|caeca]], increasing the absorption of water and electrolytes from the urinary waste.

The '''coprodeum''' is the most cranial division of the cloaca. It is the continuation of the colon where faeces are stored. It is bounded by the '''coprourodeal fold'''. It can be stretched by the faecal pressure so the central opening is everted through the vent.

The '''coprodeum''' is the most cranial division of the cloaca. It is the continuation of the colon where faeces are stored. It is bounded by the '''coprourodeal fold'''. It can be stretched by the faecal pressure so the central opening is everted through the vent.

The '''urodeum''' is the middle part of the cloaca. It is caudal to the '''proctodeum fold'''. It is the uteric opening in  the dorsolateral wall above the papilla of the deferent duct/[[Avian Female Reproductive System#Oviduct|oviduct]] opening.

The '''urodeum''' is the middle part of the cloaca. It is caudal to the '''proctodeum fold'''. It has the ureteric opening in  the dorsolateral wall above the papilla of the deferent duct/[[Avian Female Reproductive System#Oviduct|oviduct]] opening.

[[Image:Bursa of Fabricus.jpg|thumb|right|250px|Bursa of Fabricus - Copyright Nottingham 2008]]

[[Image:Bursa of Fabricus.jpg|thumb|right|250px|Bursa of Fabricus - Copyright Nottingham 2008]]

==The Vent==

==The Vent==

The vent is a horizontal slit. It is the [[Avian Male Reproductive Tract - Anatomy & Physiology#Phallus|phallus]] of males on the internal surface of the ventral lip. During insemination, the vent is inverted.

The vent is a horizontal slit. It has the [[Avian Male Reproductive Tract - Anatomy & Physiology#Phallus|phallus]] of males on the internal surface of the ventral lip. During insemination, the vent is inverted.

==Histology==

==Histology==

The avian vent and cloaca consist of columnar epithelium. Stratified squamous epithelium are present at the external opening of vent and in the '''caudal proctodeum'''. There are broad folds of mucous membrane forming crypts, which branch near their base. Lymphoid tissue is present in the submucosa. The fold of mucous membrane covering the entrance to the bursa is composed of; columnar epithelium, muscle, connective tissue and goblet cells. There are 2 layers of tunica muscularis; '''inner circular''' and '''outer longitudinal'''.

The avian vent and cloaca consist of columnar epithelium. Stratified squamous epithelium are present at the external opening of the vent and in the '''caudal proctodeum'''. There are broad folds of mucous membrane forming crypts, which branch near their base. Lymphoid tissue is present in the submucosa. The fold of mucous membrane covering the entrance to the bursa is composed of columnar epithelium, muscle, connective tissue and goblet cells. There are two layers of tunica muscularis; '''inner circular''' and '''outer longitudinal'''.

==Species Differences==

==Species Differences==

[[Category:Avian Alimentary System - Anatomy & Physiology]]

[[Category:Avian Alimentary System - Anatomy & Physiology]]

[[Category:Avian Reproduction]]

[[Category:Avian Reproduction]]