In one experiment in which electric shock was applied to Paramecium cells to trigger trichocyst discharge the macronucleus in one cell was observed to undergo morphological changes of two types. First, a large area of the nucleus, normally found to contain electron-opaque foci, had changed into whorls of more electron-transparent filamentous material. Secondly, a section of the nuclear envelope had folded into a stack like the annulate lamellae seen in oocytes of many vertebrate and invertebrate cells (see Kessel, Int. Rev. Cytol. 82:181-303, 1983). The nuclear pores were present in part of this stack of the nuclear envelope while in other parts the pores were reduced or absent and a layer of dots or lines occupied the nucleoplasmic space between the two envelope segments. Presumably these annulate lamellae represent a temporary storage mechanism for excess nuclear envelope. TEM taken on 2/28/84 by R. Allen with Zeiss 10A operating at 80kV. Neg. 12,000X. Bar = 0.5µm.
Standard glutaraldehyde fixation followed by osmium tetroxide, dehydrated in alcohol and embedded in an epoxy resin. Microtome sections prepared at approximately 75nm thickness. The negative was printed to paper and the image was scanned to Photoshop. This digitized image is available for qualitative analysis. Additional information available at (http://www5.pbrc.hawaii.edu/allen/).
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