LIPID SYNTHESIS, INTRACELLULAR TRANSPORT, AND SECRETION
Open Access
- 1 July 1967
- journal article
- research article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 34 (1), 251-263
- https://doi.org/10.1083/jcb.34.1.251
Abstract
In the mammary glands of lactating albino mice injected intravenously with 9,10-oleic acid-3H or 9,10-palmitic acid-3H, it has been shown that the labeled fatty acids are incorporated into mammary gland glycerides. The labeled lipid in the mammary gland 1 min. after injection was esterified form (> 95%), and the radioautographic reaction was seen over the rough endoplasmic reticulum and over lipid droplets, both intracellular and intraluminal. At 10-60 min after injection, the silver grains were concentrated predominantly over lipid droplets. There was no concentration of radioactivity over the granules in the Golgi apparatus, at any time interval studied. These findings were interpreted to indicate that after esterification of the fatty acid into glycerides in the rough endoplasmic reticulum an in situ aggregation of lipid occurs, with acquisition of droplet form. The release of the lipid into the lumen proceeds directly and not through the Golgi apparatus, in contradistinction to the mode of secretion of casein in the mammary gland or of lipoprotein in the liver. The presence of strands of endoplasmic reticulum attached to intraluminal lipid droplets provides a structural counterpart to the milk microsomes described in ruminant milk.Keywords
This publication has 23 references indexed in Scilit:
- LIPID SYNTHESIS, INTRACELLULAR TRANSPORT, STORAGE, AND SECRETIONThe Journal of cell biology, 1967
- Formation of milk glycerides in lactating mice, studied by electronmicroscopic autoradiography.1966
- Visualization of intravenously injected 9, 10-3-H2-palmitic acid in rat liver by electronmicroscopic autoradiography.1966
- Membranous Material of Bovine Milk Fat Globules. I. Comparison of Membranous Fractions Released by Deoxycholate and by Churning*Biochemistry, 1965
- Uptake of free fatty acids and chylomicron glycerides by guinea pig mammary gland in pregnancy and lactationJournal of Lipid Research, 1964
- Comparative properties of microsomes from cow's milk and from mammary gland. 1. Enzymic activitiesBiochemical Journal, 1958
- Effects of Varying the Vehicle for OsO4 in Tissue FixationThe Journal of cell biology, 1957
- A SIMPLE METHOD FOR THE ISOLATION AND PURIFICATION OF TOTAL LIPIDES FROM ANIMAL TISSUESJournal of Biological Chemistry, 1957
- Synthetic Activity of a Single Epithelial Cell of the Lactating Goat UdderNature, 1954
- The lipoprotein particles in cow's milkBiochemical Journal, 1954