It is an 8 to 10 centimeter long tube extended from uterus to the vestibule of the vagina which is situated at the back side of urinary bladder and urethra and in front of the rectum and anus path. The anterior wall of the vagina of an adult woman is longer than the posterior wall and the vagina makes right angle with uterus. The vagina is that place where the semen ejaculated from the penis gathers after sexual intercourse and there is a birth canal for the child at the time of delivery through which the child comes out. 

     The walls of vagina are made of smooth and fibroelastic connecting tissues and because of this reason the vagina has excessive expanding capacity and blood ducts and nerves in them supply in them. Generally, the walls of the vagina are stuck to each other but they get separate to each other when the penis enters into the vagina. Four vacant places appear on the front, back and lateral sides if the cervix protrudes in the vagina and they are called fornices and it is called fornix in singular number.  

The walls of vagina are made of two layers.

Muscular layer:

     In this layer, there are perpendicular, circular fibers and fiborous flexible connecting tissues of the smooth muscle. Due to this reason, the vagina can expand and contracts very much.

Mucous layer:

     It is an internal layer of mucus membrane which unstratified to the muscular layer in which there are several rugae. This layer is mantled by the stratified squamous epithelium viz by nonkeratinizing skin in which there is no hair. This layer becomes thick and is filled with glycogen as the adolescence period of the girl starts. There is no gland in it. The secretion mucus comes from the glands present in the cervix for keeping the vagina smooth and lubricant and this secretion is alkali but the bacteria (dordlin basilie) found in the vagina naturally changes the glycogen present in the mucus layer into the lactic acid of which the reaction of secretion of vagina becomes acidic whereby there is no doubt of any kind of infection in the vagina.

     The acidic atmosphere is adverse for the sperms but the secretions excreted by the subsidiary glands of the penis are alkali which helps in deactivating the acidity of the vagina. At the time of ovulation, the glands of cervix secrete alkali mucus in excessive quantity.