In 2005, Peter Hartmann and his team at The University of Western Australia, published a study that redefined the anatomy of the lactating human breast.1
The study used ultrasound imaging to investigate breast anatomy of 21 fully lactating women who were 1-6 months post-partum. These women were: Caucasian; between the ages of 22-38 years; with a parity of 1-4; mothers of healthy term infants; and exclusively breastfeeding.
The key findings were:
The average number of ductal openings is 9, ranging from 4-18. (This differs from previous teaching from a textbook used by many, Gray’s Anatomy, of 15-20 lobes and milk ducts.)
All ducts branch within the areolar radius, very close to the nipple.
Lactiferous sinuses do not exist. From the study, “The low number and size of ducts, the rapid branching under the areola and the absence of sinuses suggest that ducts transport breast milk, rather than store it.” (Reference 1)
The milk ducts at the base of the nipple are superficial, small and easily compressed - making them easy to occlude.
It’s not a tidy system. The course of the ducts is convoluted, lobes are merged and sometimes sitting one on top of the other.
The majority of glandular tissue is found within a 30-mm radius of the base of the nipple. (30 millimeters = 3 centimeters = 1.18 inches)
This is an important study to be aware of when asked questions about the anatomy of the lactating breast. Also, think of the implications of this information on the latch, hand expression, nipple shield sizing, and breast surgery.
Ramsay DT, Kent JC, Hartmann RA, Hartmann PE. Anatomy of the lactating human breast redefined with ultrasound imaging. J Anat. 2005;206:525-534.