This muscular canal extends from the midpoint of the cervix to its opening located between the urethra and rectum. The mucous membrane lining the vagina and musculature are continuous with the uterus. The epithelium lining the vagina thickens and produces lubricating substances in response to estrogen . These secretions aid in sexual intercourse. The breasts are milk producing glands located over the pectoral muscles consisting of a nipple, lobes, ducts and fibrous and fatty tissue.
Nipple erection is produced with stimulation.
The 15 to 25 lobes of each breast are further divided in lobules that are separated and supported by fibrous tissue. Each lobule contains small saclike aveoli surrounded by milk producing cells and small muscular cells. The muscular cells contract to express the milk during lactation. The lobules are drained by ducts that empty into a larger reservoir that lies just below the nipple. Reproductive hormones are important in the development of the breast in puberty and in lactation.