The tight junction at the bile canniculus of mouse liver contains a packed hexagonal particle array in the intercellular space. This region has been identified in freeze-etch preparations revealing several additional structures.Mouse liver is fixed in 2% purified glutaraldehyde for 2 hours and infiltrated with 20% glycerine for 1/2 hour. Fixative and cryoprotective solutions are prepared in sodium-free Krebs-Ringer phosphate pH 7.2 to 7.4 and the solutions are oxygenated before use. Fixation and infiltration are conducted at room temperature prior to quick freezing in liquid propane. Freeze-etch replicas are produced with a modified simple freeze-etch device, cleaned with “Clorox”, washed with distilled water and examined unsupported on 300 mesh grids in a Seimens Elmiskop 1A.Two different views of the Plasmalemma are observed (Fig.1). The intercellular surface is identified by the hexagonal particle array. Outside the tight junction this surface has a dense randomly distributed particle population. Viewed from the intracellular surface a circumscribed area reflects the closer membrane apposition of the occluding junction.

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A multiple ton, New Hampshire and Rhode Island Red allelic series affecting feather color in the do-breeds of fowl. 2. Inheritance studies from whole mestic fowl. Poultry Sci. 28: 782. feather extracts. Poultry Sci. 44: 47-52.

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Many evenly spaced papillae on the surface of the unfertilized egg of Strongylocentrotus purpuratus are revealed with great clarity by freeze etching. They measure about 0.25 μ in diameter and 0.5 μ in length. When flat fracture planes through the cortical granules are obtained, differential etching causes the internal components to appear similar to the structures seen in sectioned eggs. The folded laminar component stands out with a distinctive texture. At fertilization, basic structural subunits 40-45 A° in diameter, originating from ruptured cortical granules, become organized on the inner surface of the vitelline membrane to form an array of closely packed, parallel, 197 A° wide strands diagonally striated by regularly repeating units 108 A° apart at an angle of about 72° to the long axes of the strands.Figure 1 is a surface replica of the fertilization membrane as it appears 90 seconds after fertilization. As in the replicas of isolated and dried fertilization membranes made by Inoue et al. the strands extend into the somewhat regularly spaced shallow protrusions on the membrane surface.