[Distribution of oxygen tension in breast tissues]

Using a mathematical model which describes the O2, transport in the alveolar cell of the mammary gland, the distribution of pO2 levels during two stages of the secretory cycle, was calculated. At the initial stage, the typical feature of which is the increased blood flow and O2 consumption, pO2 in the secretory tissue varied from 3 to 30 torr (average 9.9 torr). At the later stage of the secretory cycle characterized by the decreased blood flow and O2 consumption, pO2 levels in the secretory tissue were within the limits of 40--60 torr (average 48.9 torr). The increase of blood flow usually observed at the initial stage of the secretory cycle seems to supply tissues with the necessary amount of O2 even if the capillarization of the alveoli is minimal.