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==Mammary Glands==
 
==Mammary Glands==
The mammary gland is a modified sweat gland that nourishes the young. It consists of the '''mamma''' and the '''teat'''. Undeveloped in both the male and female at birth, the female mammary gland begins to develop as a secondary sex characteristic at puberty. With the birth of the first young, and first lactation, the mammary gland attains its full size and function. When suckling by the young stops, milk production ceases and the gland regresses. Shortly before the next and subsequent parturitions, the gland is stimulated by hormonal changes to produce milk.
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The '''mamma (pleural = mammae) ''' is the glandular structure associated with a '''papilla '''(teat) and may contain one or more duct systems. The '''udder''' is a term designating all the mammae in the mare. The '''lobes''' are the internal compartments of the mamma, separated by adipose tissue. The lobes are divided into '''lobules''', consisting of connective tissue containing '''alveoli''', which are clusters of milk secreting cells. The '''lactiferous ducts''' are large ducts conveying milk from the alveoli to the '''lactiferous sinus'''. The openings of the lactiferous ducts convey milk formed in the alveolus to the gland sinus.  
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The '''mamma (pleural = mammae) ''' is the glandular structure associated with a '''papilla '''(teat) and may contains two ducts in the mare. The '''udder''' is a term designating all the mammae in the mare. The mammary glands of the mare are close together, forming a small udder in the inguinal region. There is an '''intermammary groove''' separating the left and right halves. Each half comprises a single mammary complex, which each has two mammary units. The '''lobes''' are the internal compartments of the mamma, separated by adipose tissue. The lobes are divided into '''lobules''', consisting of connective tissue containing '''alveoli''', which are clusters of milk secreting cells. The '''lactiferous ducts''' are large ducts conveying milk from the alveoli to the '''lactiferous sinus'''. The openings of the lactiferous ducts convey milk formed in the alveolus to the gland sinus.  
    
The '''lactiferous sinus''' (milk sinus) is the milk storage cavity within the teat and glandular body. The '''gland sinus''' is part of the milk sinus within the glandular body and the '''teat sinus''' is part of the milk sinus within the teat.  
 
The '''lactiferous sinus''' (milk sinus) is the milk storage cavity within the teat and glandular body. The '''gland sinus''' is part of the milk sinus within the glandular body and the '''teat sinus''' is part of the milk sinus within the teat.  
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The '''teat''' is the projecting part of the mammary gland containing part of the milk sinus. The '''papillary duct '''(teat canal) is the canal leading from the teat sinus to the teat opening and may be single or multiple. The '''ostium '''(teat opening) is the opening of the papillary duct and the exit point for milk or entrance point for bacteria. The '''sphincter''' consists of muscular fibres surrounding the teat opening that prevent milk flow except during suckling or milking.
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The '''teat''' is the projecting part of the mammary gland containing part of the milk sinus. The '''papillary duct '''(teat canal) is the canal leading from the teat sinus to the teat opening and may be single or multiple. The '''ostium '''(teat opening) is the opening of the papillary duct and the exit point for milk or entrance point for bacteria. The '''sphincter''' consists of muscular fibres surrounding the teat opening that prevent milk flow except during suckling or milking. The teats are short in the mare. In late pregnancy, sebacious secretions, epithelial debris and colustrum escape and accumulate around the teat; giving it a waxy appearance. This 'waxing up' can be a sign of impending parturition.
    
===Vasculature===
 
===Vasculature===
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