FEMALE EXTERNAL GENITALIA (VULVA ) & BREASTS

 STD-12      UNIT-6     CHA-3

HUMAN REPRODUCTION

FEMALE EXTERNAL GENITALIA (VULVA ) & BREASTS

FEMALE EXTERNAL GENITALIA (VULVA )

• The external genitalia are collectively called the vulva that consists of the following structures.  

• Mons pubis.  It is the anterior most portion of the external genitalia which is a cushion of fatty tissue covered by skin and pubic hair.  
• Clitoris.  Posterior to the mons pubis is the clitoris which is homologous to glans penis of the male.  It contains erectile tissue.  Clitoris differs from male penis as it is very much reduced in size and does not have any passage (it is solid struc ture, however, male penis has urethra).  There are present urethral ori lice (urethral opening) and vaginal orifice (vaginal opening) in the mid line of the vulva.  
• Labia majora.  These are two large fleshy folds of skin which The external genitalia in the form the boundary of vulva.  They are partly covered by pubic hair and contain large number of sebaceous (oil glands. The labia majora are considered homologous to the scrotum of the male. 
• Labia minora. These are two smaller folds of skin which lie under the labia majora.  Labia minora are homologous to penile urethra of male. Posteriorly the labia minora are fused together to form the fourchette. They also contain numerous sebaceous glands. The arca between the labia minora is called the vestibule. 
• Perineum. It is the area which extends from the fourchette to the anus

• Glands. 
• Vestibular glands. These are of two types. The lesser vestibular glands (= Paraurethral glands or glands of Skene) are numerous minute glands that are present on either side.  of the urethral orifice (opening). 
• These glands are homologous to the male prostate and secrete mucus. 
• The greater vestibular glands (= Bartholin's glands ) are paired glands, situated one on each side of the vaginal orifice (opening). 
• These glands are homologous to the bulbo - urethral ( Cowper's ) glands of male and secrete viscid Muid that supplements lubrication during sexual intercourse

BREASTS

• The breasts are two rounded prominences that lie over the pectoralis major muscles on the front wall of the thorax. They are also present in the male but only in rudimentary form. 
• In the female, they are undeveloped until puberty puberty in females.a they begin to develop under the influence of oestrogen and progesterone hormones . 

• Externally , each breast has projection , the nipple sur rounded by circular pigmented area of skin ( deep pink to light brown ) called areola On the surface of the areola there are numerous sebaceous glands called areolar glands . 
• Internally , the breast consists of the glandular tissue forming mammary glands . the fibrous tissue ( connective tissue ) and the fatty or adipose tissue . Mammary glands are modified sweat glands . 
• The glandular tissue comprises about 15-20 mammary lobes in each breast . 
• Each lobe is made up of a number of grapelike clusters of milk secreting structures termed alveoli . 
• When milk is produced it passes from the alveoli into the mammary tubules and then into the mammary ducts . Near the nipple , mammary ducts expand to form mammary ampullae lactiferous sinuses ) where some milk may be stored before going to lactiferous ducts . 
• Each lactiferous duct typically carries milk from one of the lobes to exterior 
• The fibrous tissue ( connective tissue ) supports the alveoli and the ducts.
• The fatty or adipose tissue is found between the lobes and covers the surface of the gland . 
• The amount of the adipose tissue determines the size of the breasts . 
• Main functions of the mammary glands are secretion and ejection (release) of milk . 
• These functions are called lactation . Lactation is associated with pregnancy and child birth . 
• Milk production is stimulated largely by the hormone prolactin secreted by anterior lobe of the pituitary gland . 
• The ejection of milk is stimulated by the hormone oxytocin , released from the posterior lobe of the pituitary gland . 
• Human milk consists of water and organic and inorganic substances , Its main constituents are fat ( fat droplets ) , casein ( milk protein ) , lactose (milk sugar ) , mineral salts ( sodium , calcium, potassium , phosphorous , etc. ) and vitamins . 
• Milk is poor in iron content . 
• Vitamin C is present in very small quantity in milk . The process of milk secretion is regulated by the nervous system . It is also influenced by the psychic state of the mother . 
• The process of milk production is also influenced by hormones of the pituitary gland ( already mentioned ) , the ovaries and other endocrine glands . 
• A nursing woman secretes 1 to 2 liters of milk per day Inhibitory Peptide . Milk contains an inhibitory peptide . 
• If the mammary glands are not fully emptied the peptide accumulates and inhibits milk production . 

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