Abstract
1. Homogenization of the epithelial cells of rabbit small intestine in 0.3m-sucrose-5mm-EDTA, pH7.4, maintains intact the microvillus sheets that form the lumenal surface of the cells, the nuclei, the mitochondria and the vesicles (microsomes) formed from the endoplasmic reticulum. 2. These particulate components of the cell, and the cell-sap fraction, have been isolated by differential centrifuging of cell homogenates. 3. The nuclei and microvillus sheets sediment together and it has been impossible to separate these subcellular components by centrifugal methods. 4. The isolated subcellular fractions have been identified by a combination of light-microscopic examination, electron-microscopic examination, chemical analysis and assay for selected enzyme activities.