Electron Microscope Studies of the Structure of the Microvilli on Principal Epithelial Cells of Rat Jejunum After Treatment in Hypo- And Hypertonic Saline

Abstract

Immersion of the intestinal tissue, from rat jejunum, in hypertonic saline produced very rapid changes in all regions of the epithelial cells, but the apical region was apparently unaffected by hypotonic solutions for at least ½ hour. In both cases, blistering of the microvilli was taken as the first sign of degenerative changes which finally resulted in a breakdown to large vesicular particles. Consideration of both normal and modified tissue indicates that the core of the microvillus contains either paired strands or tubular structures. Lateral cross-fibres extended from the core to the microvillus membrane and may be an essential part of the supporting structure of the microvillus. Densitometer traces across the microvillus membrane at various stages of modification indicated that this membrane might include a 75 A unit membrane structure with additional components associated at either surface. Interruptions in the membrane were apparently expanded by the hypotonic solutions and these might possibly be distinguished from preparative artefacts.

The fine structure of digestive‐gland cells of Helix, Succinea and Testacella

“…With the electron microscope, the cytoplasm which contains RNA is found to contain ergastoplasm; and immediately apical to the nucleus there is a typical lamellar-vacuolar field of the Gold apparatus. A variety of axial structures have been found in microvilli from mammalian epithelia, usually either filaments or tubules (Palay & Karlin, 1959;Brown, 1962;Hanssen & Herman, 1962;Millington & Finean, 1962;Kjaerheim, 1963;McNabb & Sandborn, 1964). A wide variety of methods of fixation was used by these workers.…”

Studies on the Organization of the Brush Border in Intestinal Epithelial Cells

“…The lengths of microvilli varied from 0.6 to 2.2 micra, the longest being slightly longer than have been observed in tissue sections. It is possible that these longest microvilli represent a distortion due to the osmotic shock to which the isolation procedure subjects them; increase in length is a typical response of microvilli to treatment with hypotonic solutions (18).…”

Photoreceptor Organelles in Animals

“…I and 3). Goldsmith also saw a dark core or strand in the centre of the rhabdomere tubules (honey-bee ommatidium); it is just possible that this may bear some similarity to the 'paired strands or tubular structures' seen by Millington & Finean (1962) in the microvilli of jejunum epithelial cells. The junctional region where the tubules join the retinula cell presents interesting 5-2 structural problems.…”