Formation of the milk fat globule membrane without participation of the plasmalemma

Abstract

In goat mammary tissue under certain conditions perfusion fixation produces a considerable swelling of the rough endoplasmic reticulum and the appearance, in a small number of cells, of intracellular vacuoles which contain lipid globules and casein particles. The morphological evidence suggests that these vacuoles form by fusion of Golgi vesicles. By this process the characteristic structure of the milk fat globule membrane (MFGM) is produced around the lipid globules without any contribution from the plasmalemma. This corroborates the earlier suggestion that normal MFG secretion involves the Golgi vesicles directly.