ISSN:
1432-1424
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary Pieces of rabbit gallbladders were incubated in vitro for 1 hr in Ringer's solution at 37° (“transporting epithelium”), or in Ringer's containing 1mm ouabain (“inhibited epithelium”). The tissues were fixed in 2% glutaraldehyde, postfixed in OsO4 and embedded in Epon. Stereological analysis was carried out on electron micrographs; with this type of analysis it is possible to obtain quantitative data for the three-dimensional structure of the tissue. The following data were obtained for crest transporting epithelium (crypt epithelium in parentheses): Epithelial height, 28 (18) μm; nucleus, 16.9 (18.7) % of cell volume; mitochondria, 18.7 (14.1) % of cytoplasmic volume; paracellular channels, 28.3 (11.0)% of epithelial volume; lateral plasma membrane, 4.1 (2.9) m2/cm3, and apical membrane, 0.5 (0.6) m2/cm3 of cell volume. The paracellular channels appeared as interconnected tissue sheets of a highly varying width. They were broader in the basal portion of the epithelium than in the apical portion; however, immediately above the basement membrane the channels became very narrow. The arithmetic mean width of the channels was 0.9 (0.2) μm and their length was in the range of 40–120 μm. Our stereological data seem compatible with the standing gradient model for water transport. The ouabain inhibited cells were swollen with collapsed paracellular channels. It cannot be ruled out that volume changes occurred in the cells and the paracellular channels during the processing of the tissue. However, qualitatively the same morphology was observed by light microscopy of transporting and inhibited gallbladder epithelium fixed by freeze-drying and embedded in Epon. This constitutes a strong indication of the presence of such channels in the living, in vitro transporting rabbit gallbladder epithelium.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01940923
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