To investigate the extent to which the electron-opaque pore material can regulate nucleocytoplasmic exchanges which occur through the nuclear annuli, experiments were performed in which polyvinylpyrrolidone (PVP)-coated colloidal gold particles (25 to 170 A in diameter) were microinjected into the cytoplasm of amebas (Amoeba proteus). The cells were fixed at various times after injection and examined with the electron microscope in order to determine the location of the gold particles. High concentrations of gold were found associated with the pore material at specific points adjacent to and within the pores. It is tentatively suggested that such specific accumulations could be a means of selecting substances from the cytoplasm for transport through the pores. Particles were also scattered throughout the ground cytoplasm and nucleoplasm. A comparison of the diameters of particles located in these two regions showed that the ability of materials to penetrate the nuclear envelope is a function of their size. It was estimated that the maximum size of the particles able to enter the nucleus is approximately 125 to 145 A indiameter. The regulation of exchanges with regard to particle size is thought to be dependent on the specific organization of the electron-opaque pore material.
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Article| April 01 1965
THE EFFECT OF THE ELECTRON-OPAQUE PORE MATERIAL ON EXCHANGES THROUGH THE NUCLEAR ANNULI
Carl M. Feldherr
From the Department of Physiology, University of Alberta, Edmonton, Canada.
The author's present address is Department of Anatomy, University of Pennsylvania, Philadelphia
Received: April 16 1964
Online ISSN: 1540-8140
Print ISSN: 0021-9525
Copyright © 1965 by The Rockefeller Institute Press
Carl M. Feldherr; THE EFFECT OF THE ELECTRON-OPAQUE PORE MATERIAL ON EXCHANGES THROUGH THE NUCLEAR ANNULI . J Cell Biol 1 April 1965; 25 (1): 43–53. doi: https://doi.org/10.1083/jcb.25.1.43
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