Studies have been made on normal tissue from 50 whole breasts
and 43 breast biopsies using subgross histological and duct
injection techniques. The results obtained from the various
investigations have been compared with factors which may affect the
breast, notably age, the menstrual cycle, parity and laterality.
It has been found that the ducts in the breast do not branch in
a simple dichotomous manner, nor are individual lactiferous systems
arranged about the nipple in discrete lobes like the spokes of a
wheel. Rather, the duct systems are interwoven with each other in
an intricate manner and may not be dissected out individually.
The quantity of parenchymatous lobules in the breast was found
to decrease significantly with age. Lobules occurred in areas of
high focal density and their number was not related to the amount
of fibrous stroma present. Lobules did not occur with greater
frequency in the upper outer quadrant of the breast and lobule
number was not related to tumour incidence. Parity and laterality
were without significance in the present study.
The presence of acid mucopolysaccharides in the intra-lobular
breast stroma showed a cyclical variation which peaked at approx¬
imately day 24 of the menstrual cycle. It is suggested that
hyaluronic acid is the principal component of the staining reaction
and may be associated with premenstrual water retention in the
breast. The incidence of intraluminal secretions within the
ductules of lobules, and intracellular granules within ductular cells, did not reveal cyclical variation.
Normal lobule types occurring in whole breasts were assessed by
subgross techniques and significant variations were recorded with
age. Parity and laterality were not of significance in these
results. Examination of breasts following injection of lactiferous
ducts with a radio-opaque medium indicated that more than one
subgross lobule type was associated with a single lactiferous duct
system.
Comparisons have been made between the radiographic and
subgross morphology of slices of breast tissue and results suggest
that the parenchymal content of the breast cannot be predicted from
radiographic appearances alone
