Abstract
Enterolipomicrons, small particles visible in dark field preparations, appear in Thiry loops of duodenum or jejunum on physiological stimulation. Usually, debris consists of desquamating, disintegrating mucosal cells; mucous material is obtained at the same time. The particles differ from the debris in composition and enzyme activity, and their appearance and their composition suggest a cytoplasmic origin. In electron microscope preparations of resting mucosa, similar particles can be seen in large numbers in the cells whereas in vigorously stimulated preparations they are scarce. It is concluded that the centrifugal fraction normally called enterolipomicron consists of a mixture of secretory granules actually secreted and of cytoplasmic microsomal material derived from disintegrating cells. The fraction has considerable enzymatic activity.