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Intramembrane particle structures in epithelial cells of the toad urinary bladder: a quantitative freeze‐fracture study
Author(s) -
Shinowara Nancy L.,
Palaia Thomas A.,
Discala Vincent A.
Publication year - 1989
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1111/j.1768-322x.1989.tb00818.x
Subject(s) - toad , membrane , cytoplasm , biology , biophysics , particle (ecology) , cell membrane , basal (medicine) , microbiology and biotechnology , vesicle , tight junction , antidiuretic , biochemistry , hormone , endocrinology , ecology , insulin
Freeze‐fracture electron microscopy reveals intramembrane particle arrays in basal membranes of granular epithelial cells as well as both upper and lower plasma membranes of the underlying basal cells in the toad urinary bladder. These particle arrays are morphologically indistinguishable from the luminal membrane aggregates which are known to be associated with antidiuretic hormone (ADH)‐stimulated water transport. In both granular and basal cells particle arrays are frequently located in and/or around the openings of vesicular and/or tubular structures fused to the plasma membranes, suggesting that they may be transferred from the cytoplasm by membrane fusion. Quantification of cytoplasmic aggrephores in control granular cells shows that they can be numerous and as close to the basolateral membrane as they are with the luminal membrane, to which they are known to fuse and deliver aggregates upon ADH stimulation. Aggrephore‐like tubules were also found in the basal cells. Particle array densities were quantified for 6 pairs of control and ADH‐stimulated hemibladders. At least 1440 μm 2 area of plasma membrane for each membrane domain was examined. Results indicate that the presence of these particle arrays in granular and basal cell membranes is highly variable and that exposure to ADH does not cause a statistically significant increase in their frequency.