part of breast mammary gland BTO:0000817 BrendaTissueOBO Brustdruese The specialized accessory gland of the skin of female mammals that secretes milk. In the human female, it is a compound tubuloalveolar gland composed of 15 to 25 lobes arranged radially about the nipple and separated by connective and adipose tissue, each lobe having its own excretory (lactiferous) duct opening on the nipple. The lobes are subdivided into lobules, with the alveolar ducts and alveoli being the secretory portion of the gland. glandula mammaria lactiferous gland mamma