SummaryIt has been claimed by Stewart, Puppione & Patton (1972) that milk is a valuable source of cell membrane in a ‘relatively pure’ state originating from shed mammary secretory cell microvilli and golgi vesicles. The morphological basis for this has been re-examined in this paper. It is shown that the vesicular and elongated membranous structures found in skim-milk are identical to structures present as part of the initial milk fat globule membrane (MFGM) of alveolar and expressed milk, and that both structures survive extraction with chloroform–methanol. It is therefore suggested that a major part of the skim-milk membrane is material shed from the freshly secreted milk fat globule and consists of a specialised derivative of the secretory cell plasmalemma, the initial MFGM.
Oxidation of Milk Fat Globule Membrane Material. I. Thiobarbituric Acid Reaction as a Measure of Oxidized Flavor in Milk and Model Systems