Physicochemical Analyses of the Bovine Milk Fat Globule Membrane. II. Electron Microscopy

Abstract

Samples of cream and milk fat globule membrane fractions from bovine milk were examined by electron microscopy with thin sectioning and freeze-etching. Certain components of the fat globule membrane aggregated inside the continuous envelope surrounding the globule. At the site of aggregates the trilaminar electron microscopie image is similar to that of a normal cytoplasmic membrane, tIowever, most of the membrane, contiguous with fat of the globule, exhibited no trilaminar structure. This difference in the structure of the membrane at various points is probably due to a re-arrangement of its components. Freeze-etching provided further evidence of the orientation of a layer of triglyceride crystals adjacent and parallel to the membrane in fat globules.