In addition to plates the plasma membrane contains IMPs on its P-fracture face in ring or parenthesis shape at sites of trichocyst secretion. A ring actually consists of two circles of IMPs and signifies that a trichocyst is docked underneath while a parenthesis means the site has no docked trichocyst. The fracture also exposed some of the E-face of the outer alveolar membrane which is relatively free of IMPs. TEM taken on 6/4/90 by R. Allen with Zeiss 10A operating at 80kV. Neg. 19,800X. Bar = 0.25µm. There is a high resolution version of this image in the library (CIL:39318) which is available for quantitative analysis. Additional information available at (http://www5.pbrc.hawaii.edu/allen/).