Changes

:* '''''Sprague Dawley:''''' Multipurpose breed of albino rat used extensively in medical research due to its calmness and ease of handling.  They are prolific (average litter: 10.5), with a lifespan of 2.5-3.5 years and a tail longer than the body.

:* '''''Sprague Dawley:''''' Multipurpose breed of albino rat used extensively in medical research due to its calmness and ease of handling.  They are prolific (average litter: 10.5), with a lifespan of 2.5-3.5 years and a tail longer than the body.

:* '''''Long-Evans:'''''  Multipurpose model organism (frequent in behavioral and obesity research).  Developed by crossing Wistar females with a wild gray male.  They are white with a black or brown hood (=head and shoulders).

:* '''''Long-Evans:'''''  Multipurpose model organism (frequent in behavioral and obesity research).  Developed by crossing Wistar females with a wild gray male.  They are white with a black or brown hood (=head and shoulders).

[[Image:Inbred_rat_lines.jpg|thumb|200px|'''Zucker Rat''' <br> Joanna Servaes 2006, WikiMedia Commons]]

[[Image:Inbred_rat_lines.jpg|thumb|200px|'''Zucker Rat''' <br> Joanna Servaes 2006, WikiMedia Commons]]

:* '''''RCS:''''' Royal College of Surgeons rat, with inherited retinal degeneration.

:* '''''RCS:''''' Royal College of Surgeons rat, with inherited retinal degeneration.

:* '''''Shaking rat Kawasaki:''''' Deficient in cortex lamination and cerebellar development

:* '''''Shaking rat Kawasaki:''''' Deficient in cortex lamination and cerebellar development

====Transgenic rats====

====Transgenic rats====

==Anatomy and Histology==

==Anatomy and Histology==

[[Image:Ventral organ layout rat.jpg|thumb|left|400px|Organ topography in the rat, ventral view.]]

[[Image:Ventral organ layout rat.jpg|thumb|left|200px|Organ topography in the rat, ventral view.]]

 

 

This summary <ref name="Percy"> Percy, D.H. and Barthold, S.W. (2007). “Rat”, In: ''Pathology of laboratory rodents and rabbits''. Percy, D.H. and Barthold, S.W. (Eds.). Blackwell Publishing. pp. 125-178</ref><ref name="Boorman">''Pathology of the Fischer Rat'' (1990). Boorman, G.A., Eustis, S.L., Elwell, M.R., Montgomery Jr., C.A., MacKenzie, W.F., (Eds.). Academic Press Inc.</ref> is not comprehensive and it only aims to deal with peculiarities of rat anatomy and histology.  The information on gross anatomy is from a reference on F344 rat and minor variations with other strains should be expected:

This summary <ref name="Percy"> Percy, D.H. and Barthold, S.W. (2007). “Rat”, In: ''Pathology of laboratory rodents and rabbits''. Percy, D.H. and Barthold, S.W. (Eds.). Blackwell Publishing. pp. 125-178</ref><ref name="Boorman">''Pathology of the Fischer Rat'' (1990). Boorman, G.A., Eustis, S.L., Elwell, M.R., Montgomery Jr., C.A., MacKenzie, W.F., (Eds.). Academic Press Inc.</ref> is not comprehensive and it only aims to deal with peculiarities of rat anatomy and histology.  The information on gross anatomy is from a reference on F344 rat and minor variations with other strains should be expected:

===Nervous system===

===Nervous system===

The '''''brain''''' is lissencephalic.

The '''''brain''''' is lissencephalic. The '''''spinal cord''''' is 11-12.5cm long and ends in the second lumbar vertebra.

 

The '''''spinal cord''''' is 11-12.5cm long and ends in the second lumbar vertebra.

===Vascular system and blood===

===Vascular system and blood===

The '''''heart''''' of a young adult rat is approximately 0.3% of the body weight.

The '''''heart''''' of a young adult rat is approximately 0.3% of the body weight. In the '''''blood''''' The predominant leukocyte is the lymphocyte (80%).  Eosinophils tend to have ring-shaped nuclei without lobation.  Mature male rats have higher leukocyte counts than females

 

In the '''''blood''''' The predominant leukocyte is the lymphocyte (80%).  Eosinophils tend to have ring-shaped nuclei without lobation.  Mature male rats have higher leukocyte counts than females

===Respiratory system===

===Respiratory system===

The '''''trachea''''' is slightly flattened (3mm x 2mm diameter).

The '''''trachea''''' is slightly flattened (3mm x 2mm diameter).

The '''''lung''''' has a single left lobe and four right lobes that follow the bifurcations of the bronchial tree (anterior (=apical or cranial), middle (=cardiac), median (=azygous or accessory) and posterior (=caudal)).  When the bronchi enter the lung, they divide into a major segment (at a small angle from the parent airway) and a minor segment (at a much greater angle to the parent airway).  This results in air moving at lower velocity entering the minor branch.  This is called ''monopodal branching'' and is a feature of the rat and the mouse.  A feature particular of rats is the presence of serous cells in the respiratory epithelium.

The '''''lung''''' has a single left lobe and four right lobes that follow the bifurcations of the bronchial tree (anterior (=apical or cranial), middle (=cardiac), median (=azygous or accessory) and posterior (=caudal)).  When the bronchi enter the lung, they divide into a major segment (at a small angle from the parent airway) and a minor segment (at a much greater angle to the parent airway).  This results in air moving at lower velocity entering the minor branch.  This is called ''monopodal branching'' and is a feature of the rat and the mouse.  A feature particular of rats is the presence of serous cells in the respiratory epithelium.

===Lymphoid system===

===Lymphoid system===

===Digestive system===

===Digestive system===

[[Image:Ventral_neck_organs_rat.jpg|thumb|400px|'''Rat Incisors''' <br> Alexey Krasavin 2007, WikiMedia Commons]]

[[Image:Ventral_neck_organs_rat.jpg|thumb|200px|'''Rat Incisors''' <br> Alexey Krasavin 2007, WikiMedia Commons]]

'''''Oral cavity:''''' The dental formula of the rat is 2(I 1/1; M 3/3).  Incisors are continuously erupting and are maintained at a constant length by attrition of occlusal surfaces.  This results in total renewal every 40-50 days.  Their yellow colour increases with age and is a result of iron containing pigments.

'''''Oral cavity:''''' The dental formula of the rat is 2(I 1/1; M 3/3).  Incisors are continuously erupting and are maintained at a constant length by attrition of occlusal surfaces.  This results in total renewal every 40-50 days.  Their yellow colour increases with age and is a result of iron containing pigments.

   

   

'''''Liver:'' ''' The liver has four lobes (left, median, right and caudate).  The median, right and caudate lobes are subdivided in two sublobes.  The rat has no gall bladder and the bile is not concentrated.  Hepatocyte polyploidy and binucleated cells is common and increases with age  

'''''Liver:'' ''' The liver has four lobes (left, median, right and caudate).  The median, right and caudate lobes are subdivided in two sublobes.  The rat has no gall bladder and the bile is not concentrated.  Hepatocyte polyploidy and binucleated cells is common and increases with age  

 

[[Image:ImageNeeded.png‎|thumb|left|200px|Accessory sex glands in the adult male rat]]

 

 

[[Image:ImageNeeded.png‎|thumb|left|450px|Accessory sex glands in the adult male rat]]

===Urogenital system===

===Urogenital system===

===Congenital and genetic===

===Congenital and genetic===

===Nutritional and Environmental===

===Nutritional and Environmental===

===Degenerative and Aging===

===Degenerative and Aging===

===Infectious===

===Infectious===

====Bacterial====

====Bacterial====

====Viral====

====Viral====

====Parasitic====

====Parasitic====

====Mycotic====

====Mycotic====

===Neoplasia===

===Neoplasia===

====Pulmonary lesions of unknown aetiology====

====Pulmonary lesions of unknown aetiology====

==The rat in toxicopathology==

==The rat in toxicopathology==