Obstetric and Gynecological Nursing - The Carter Center

approximately 20 sebaceous glands. In pregnancy these
enlarge and are known as montgeomery’s tubercles.
The nipple lies in the centre of the areola at the level of the
fourth rib. Aprotuberance about 6mm in length, composed of
pigmented erectile tissue.The surface of the nipple is
perforarted by small orifices which are the openings of the
lactiferous ducts. It is covered with epithelium.
Microscopic structure The breast is composed largely of
glandular tissue, but also of some fatty tissue, and is covered
with skin. This glandular tissue is divided into about 18 lobes
which are completely separated by bands of fibrous tissue.
The internal structure is said to be resemble as the segments
of a halved grape fruit or orgnge. Each lobe is a self-contained
working unit and is composed of the following structures
Alveoli: Containing the milk- secreting cells. Each alveolus is
lined by millk-secreting cells, the acini, which extract from the
mammary blood supply the factors essential for milk
formation. Around each alveolus lie myoepithelial cells,
sometimes called ‘basket’ or ‘spider’s cells. When these cells
are stimulated by oxytocin they contract releasing milk into the
lactifierous duct.
Lactifierous tubules: small ducts which connect the alveoli.
Lactifierous duct: a central duct into which the tubules run.
32