An electron microscopic study of the intestinal villus. II. The pathway of fat absorption

Electron-opaque, lipid-containing bodies in mouse liver at early intervals after partial hepatectomy and sham operation

The appearance and distribution of electron-opaque, lipid-containing bodies have been studied in liver of adult male mice of the C3H strain. The mice were either partially hepatectomized or sham-operated, and the liver was fixed in Veronal acetate-buffered 2 per cent osmium tetroxide at various postoperative intervals (10, 20, 40, 60, and 120 minutes). Normal, non-operated mice served as controls. As early as 10 minutes after both sham operation and partial hepatectomy, lipid-containing bodies have been observed, not only in the cytoplasm of hepatic parenchymal cells, but also in the space of Disse. At the very early postoperative intervals studied, minute lipid bodies are repeatedly found to be more numerous in the space of Disse than at later intervals. It is suggested that the lipid-containing bodies enter the parenchymal cell from the circulation. At the cell membrane, numerous invaginations, each containing a lipid body, have been observed; this suggests that the lipid bodies enter the hepatic parenchymal cells by the process of pinocytosis.The fact that only hepatic parenchymal cells contain the lipid bodies, whereas von Kupffer, endothelial lining, and Ito's fat-storing cells do not, may indicate a specific lipid mobilization response on the part of the cells of the hepatic parenchyma.

PROTEIN SYNTHESIS INHIBITION: MECHANISM FOR THE PRODUCTION OF IMPAIRED FAT ABSORPTION

Treatment of rats with puromycin and acetoxycycloheximide results in a defect in intestinal lipid transport. Under these conditions rats given corn oil accumulate triglyceride within the intestinal cells and fail to develop the normal postprandial hyperlipemia. The observed interference in lipid transport appears to be a consequence of impaired chylomicron formation.

THE ABSORPTION OF OLEIC ACID IN THE BILE FISTULA RAT

A technique is described for collecting thoracic duct lymph in a portable glass saddle from an unrestrained rat. Uniformly labelled oleic acid in various physical states was given to rats with thoracic duct and bile fistulae to study the influence of bile salts on the amount absorbed and on the route of transport and esterification after absorption. It is suggested that in addition to their emulsifying action bile salts may stimulate the esterification of absorbed oleic acid by the intestinal mucosa.

Electron microscopic changes associated with water absorption in the jejunum

With the electron microscope, mucosal changes induced by the instillation of water into a segment of jejunum of rats were observed. The animals had been deprived of food and water for 24 hours.

A consideration of the extraneous coats of the plasma membrane

This review is concerned with the role of the "extraneous coat" of the ameba in pinocytosis. It also considers the possible role of the extraneous coat as an additional barrier to those exchanges between the cytoplasm and the environment which involve diffusion. Several examples of pinocytosis in mammalian tissues are presented and are appraised with respect to the physical-chemical properties of the extraneous coat. Types of transport that do not appear to operate by way of pinocytosis are similarly considered.